diff --git a/.indent.pro b/.indent.pro
index e58bf0c6..b09c6396 100644
--- a/.indent.pro
+++ b/.indent.pro
@@ -59,6 +59,7 @@
 -T lxw_content_types
 -T lxw_core
 -T lxw_custom
+-T lxw_custom_property
 -T lxw_datetime
 -T lxw_defined_name
 -T lxw_doc_properties
diff --git a/include/xlsxwriter/common.h b/include/xlsxwriter/common.h
index 92e83339..6cd76c42 100644
--- a/include/xlsxwriter/common.h
+++ b/include/xlsxwriter/common.h
@@ -190,6 +190,7 @@ STAILQ_HEAD(lxw_formats, lxw_format);
 
 /* Define the queue.h structs for the generic data structs. */
 STAILQ_HEAD(lxw_tuples, lxw_tuple);
+STAILQ_HEAD(lxw_custom_properties, lxw_custom_property);
 
 typedef struct lxw_tuple {
     char *key;
@@ -198,6 +199,17 @@ typedef struct lxw_tuple {
     STAILQ_ENTRY (lxw_tuple) list_pointers;
 } lxw_tuple;
 
+/* Define custom property used in workbook.c and custom.c. */
+typedef struct lxw_custom_property {
+
+    char *name;
+    char *value;
+
+    STAILQ_ENTRY (lxw_custom_property) list_pointers;
+
+} lxw_custom_property;
+
+
 
  /* *INDENT-OFF* */
 #ifdef __cplusplus
diff --git a/include/xlsxwriter/content_types.h b/include/xlsxwriter/content_types.h
index 3697eddc..39aa8e16 100644
--- a/include/xlsxwriter/content_types.h
+++ b/include/xlsxwriter/content_types.h
@@ -39,16 +39,20 @@ extern "C" {
 
 lxw_content_types *lxw_content_types_new();
 void lxw_content_types_free(lxw_content_types *content_types);
-void lxw_content_types_assemble_xml_file(lxw_content_types *self);
-void lxw_ct_add_default(lxw_content_types *self, const char *key,
+void lxw_content_types_assemble_xml_file(lxw_content_types *content_types);
+void lxw_ct_add_default(lxw_content_types *content_types, const char *key,
                         const char *value);
-void lxw_ct_add_override(lxw_content_types *self, const char *key,
+void lxw_ct_add_override(lxw_content_types *content_types, const char *key,
                          const char *value);
-void lxw_ct_add_worksheet_name(lxw_content_types *self, const char *name);
-void lxw_ct_add_chart_name(lxw_content_types *self, const char *name);
-void lxw_ct_add_drawing_name(lxw_content_types *self, const char *name);
-void lxw_ct_add_shared_strings(lxw_content_types *self);
-void lxw_ct_add_calc_chain(lxw_content_types *self);
+void lxw_ct_add_worksheet_name(lxw_content_types *content_types,
+                               const char *name);
+void lxw_ct_add_chart_name(lxw_content_types *content_types,
+                           const char *name);
+void lxw_ct_add_drawing_name(lxw_content_types *content_types,
+                             const char *name);
+void lxw_ct_add_shared_strings(lxw_content_types *content_types);
+void lxw_ct_add_calc_chain(lxw_content_types *content_types);
+void lxw_ct_add_custom_properties(lxw_content_types *content_types);
 
 /* Declarations required for unit testing. */
 #ifdef TESTING
diff --git a/include/xlsxwriter/custom.h b/include/xlsxwriter/custom.h
index 62e86857..7483c07e 100644
--- a/include/xlsxwriter/custom.h
+++ b/include/xlsxwriter/custom.h
@@ -3,7 +3,7 @@
  *
  * Copyright 2014-2016, John McNamara, jmcnamara@cpan.org. See LICENSE.txt.
  *
- * custom - A libxlsxwriter library for creating Excel XLSX custom files.
+ * custom - A libxlsxwriter library for creating Excel custom property files.
  *
  */
 #ifndef __LXW_CUSTOM_H__
@@ -14,12 +14,15 @@
 #include "common.h"
 
 /*
- * Struct to represent a custom object.
+ * Struct to represent a custom property file object.
  */
 typedef struct lxw_custom {
 
     FILE *file;
 
+    struct lxw_custom_properties *custom_properties;
+    uint32_t pid;
+
 } lxw_custom;
 
 
diff --git a/include/xlsxwriter/packager.h b/include/xlsxwriter/packager.h
index babbaab9..76788c55 100644
--- a/include/xlsxwriter/packager.h
+++ b/include/xlsxwriter/packager.h
@@ -18,6 +18,7 @@
 #include "shared_strings.h"
 #include "app.h"
 #include "core.h"
+#include "custom.h"
 #include "theme.h"
 #include "styles.h"
 #include "format.h"
diff --git a/include/xlsxwriter/workbook.h b/include/xlsxwriter/workbook.h
index ebb4ed36..67938b3b 100644
--- a/include/xlsxwriter/workbook.h
+++ b/include/xlsxwriter/workbook.h
@@ -193,6 +193,8 @@ typedef struct lxw_workbook {
     struct lxw_defined_names *defined_names;
     lxw_sst *sst;
     lxw_doc_properties *properties;
+    struct lxw_custom_properties *custom_properties;
+
     char *filename;
     lxw_workbook_options options;
 
@@ -481,6 +483,9 @@ uint8_t workbook_close(lxw_workbook *workbook);
 uint8_t workbook_set_properties(lxw_workbook *workbook,
                                 lxw_doc_properties *properties);
 
+uint8_t workbook_set_custom_property_string(lxw_workbook *workbook,
+                                            char *name, char *value);
+
 /**
  * @brief Create a defined name in the workbook to use as a variable.
  *
diff --git a/src/content_types.c b/src/content_types.c
index 1803ea98..ec954928 100644
--- a/src/content_types.c
+++ b/src/content_types.c
@@ -329,3 +329,13 @@ lxw_ct_add_calc_chain(lxw_content_types *self)
     lxw_ct_add_override(self, "/xl/calcChain.xml",
                         LXW_APP_DOCUMENT "spreadsheetml.calcChain+xml");
 }
+
+/*
+ * Add the custom properties to the ContentTypes overrides.
+ */
+void
+lxw_ct_add_custom_properties(lxw_content_types *self)
+{
+    lxw_ct_add_override(self, "/docProps/custom.xml",
+                        LXW_APP_DOCUMENT "custom-properties+xml");
+}
diff --git a/src/custom.c b/src/custom.c
index 467227a2..5ff0a798 100644
--- a/src/custom.c
+++ b/src/custom.c
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * custom - A library for creating Excel XLSX custom files.
+ * custom - A library for creating Excel custom property files.
  *
  * Used in conjunction with the libxlsxwriter library.
  *
@@ -49,7 +49,6 @@ lxw_custom_free(lxw_custom *custom)
     free(custom);
 }
 
-
 /*****************************************************************************
  *
  * XML functions.
@@ -65,6 +64,67 @@ _custom_xml_declaration(lxw_custom *self)
     lxw_xml_declaration(self->file);
 }
 
+/*
+ * Write the <vt:lpwstr> element.
+ */
+STATIC void
+_chart_write_vt_lpwstr(lxw_custom *self, char *value)
+{
+    lxw_xml_data_element(self->file, "vt:lpwstr", value, NULL);
+}
+
+/*
+ * Write the <property> element.
+ */
+STATIC void
+_chart_write_custom_property(lxw_custom *self,
+                             lxw_custom_property *custom_property)
+{
+    struct xml_attribute_list attributes;
+    struct xml_attribute *attribute;
+    char fmtid[] = "{D5CDD505-2E9C-101B-9397-08002B2CF9AE}";
+
+    self->pid++;
+
+    LXW_INIT_ATTRIBUTES();
+    LXW_PUSH_ATTRIBUTES_STR("fmtid", fmtid);
+    LXW_PUSH_ATTRIBUTES_INT("pid", self->pid + 1);
+    LXW_PUSH_ATTRIBUTES_STR("name", custom_property->name);
+
+    lxw_xml_start_tag(self->file, "property", &attributes);
+
+    /* Write the vt:lpwstr element. */
+    _chart_write_vt_lpwstr(self, custom_property->value);
+
+    lxw_xml_end_tag(self->file, "property");
+
+    LXW_FREE_ATTRIBUTES();
+}
+
+/*
+ * Write the <Properties> element.
+ */
+STATIC void
+_write_custom_properties(lxw_custom *self)
+{
+    struct xml_attribute_list attributes;
+    struct xml_attribute *attribute;
+    char xmlns[] = LXW_SCHEMA_OFFICEDOC "/custom-properties";
+    char xmlns_vt[] = LXW_SCHEMA_OFFICEDOC "/docPropsVTypes";
+    lxw_custom_property *custom_property;
+
+    LXW_INIT_ATTRIBUTES();
+    LXW_PUSH_ATTRIBUTES_STR("xmlns", xmlns);
+    LXW_PUSH_ATTRIBUTES_STR("xmlns:vt", xmlns_vt);
+
+    lxw_xml_start_tag(self->file, "Properties", &attributes);
+
+    STAILQ_FOREACH(custom_property, self->custom_properties, list_pointers) {
+        _chart_write_custom_property(self, custom_property);
+    }
+
+    LXW_FREE_ATTRIBUTES();
+}
 
 /*****************************************************************************
  *
@@ -81,7 +141,9 @@ lxw_custom_assemble_xml_file(lxw_custom *self)
     /* Write the XML declaration. */
     _custom_xml_declaration(self);
 
-    lxw_xml_end_tag(self->file, "custom");
+    _write_custom_properties(self);
+
+    lxw_xml_end_tag(self->file, "Properties");
 }
 
 /*****************************************************************************
diff --git a/src/packager.c b/src/packager.c
index c33ee720..ef174870 100644
--- a/src/packager.c
+++ b/src/packager.c
@@ -400,6 +400,38 @@ _write_core_file(lxw_packager *self)
     return 0;
 }
 
+/*
+ * Write the custom.xml file.
+ */
+STATIC uint8_t
+_write_custom_file(lxw_packager *self)
+{
+    lxw_custom *custom;
+    int err;
+
+    if (STAILQ_EMPTY(self->workbook->custom_properties))
+        return 0;
+
+    custom = lxw_custom_new();
+
+    custom->file = lxw_tmpfile();
+    if (!custom->file)
+        return LXW_ERROR_CREATING_TMPFILE;
+
+    custom->custom_properties = self->workbook->custom_properties;
+
+    lxw_custom_assemble_xml_file(custom);
+
+    err = _add_file_to_zip(self, custom->file, "docProps/custom.xml");
+    RETURN_ON_ERROR(err);
+
+    fclose(custom->file);
+
+    lxw_custom_free(custom);
+
+    return 0;
+}
+
 /*
  * Write the theme.xml file.
  */
@@ -513,6 +545,9 @@ _write_content_types_file(lxw_packager *self)
     if (workbook->sst->string_count)
         lxw_ct_add_shared_strings(content_types);
 
+    if (!STAILQ_EMPTY(self->workbook->custom_properties))
+        lxw_ct_add_custom_properties(content_types);
+
     lxw_content_types_assemble_xml_file(content_types);
 
     err = _add_file_to_zip(self, content_types->file, "[Content_Types].xml");
@@ -679,10 +714,18 @@ _write_root_rels_file(lxw_packager *self)
         return LXW_ERROR_CREATING_TMPFILE;
 
     lxw_add_document_relationship(rels, "/officeDocument", "xl/workbook.xml");
-    lxw_add_package_relationship(rels, "/metadata/core-properties",
+
+    lxw_add_package_relationship(rels,
+                                 "/metadata/core-properties",
                                  "docProps/core.xml");
-    lxw_add_document_relationship(rels, "/extended-properties",
-                                  "docProps/app.xml");
+
+    lxw_add_document_relationship(rels,
+                                  "/extended-properties", "docProps/app.xml");
+
+    if (!STAILQ_EMPTY(self->workbook->custom_properties))
+        lxw_add_document_relationship(rels,
+                                      "/custom-properties",
+                                      "docProps/custom.xml");
 
     lxw_relationships_assemble_xml_file(rels);
 
@@ -789,6 +832,9 @@ lxw_create_package(lxw_packager *self)
     error = _write_core_file(self);
     RETURN_ON_ERROR(error);
 
+    error = _write_custom_file(self);
+    RETURN_ON_ERROR(error);
+
     error = _write_theme_file(self);
     RETURN_ON_ERROR(error);
 
diff --git a/src/workbook.c b/src/workbook.c
index 2fcf9ea5..87208f3e 100644
--- a/src/workbook.c
+++ b/src/workbook.c
@@ -58,6 +58,20 @@ _free_doc_properties(lxw_doc_properties *properties)
     free(properties);
 }
 
+/*
+ * Free workbook custom property.
+ */
+STATIC void
+_free_custom_doc_property(lxw_custom_property *custom_property)
+{
+    if (custom_property) {
+        free(custom_property->name);
+        free(custom_property->value);
+    }
+
+    free(custom_property);
+}
+
 /*
  * Free a workbook object.
  */
@@ -70,6 +84,7 @@ lxw_workbook_free(lxw_workbook *workbook)
     lxw_chart *chart;
     lxw_format *format;
     lxw_defined_name *defined_name;
+    lxw_custom_property *custom_property;
 
     if (!workbook)
         return;
@@ -106,6 +121,13 @@ lxw_workbook_free(lxw_workbook *workbook)
         free(defined_name);
     }
 
+    /* Free the custom_properties in the workbook. */
+    while (!STAILQ_EMPTY(workbook->custom_properties)) {
+        custom_property = STAILQ_FIRST(workbook->custom_properties);
+        STAILQ_REMOVE_HEAD(workbook->custom_properties, list_pointers);
+        _free_custom_doc_property(custom_property);
+    }
+
     if (workbook->worksheet_names) {
         for (worksheet_name =
              RB_MIN(lxw_worksheet_names, workbook->worksheet_names);
@@ -128,6 +150,7 @@ lxw_workbook_free(lxw_workbook *workbook)
     free(workbook->ordered_charts);
     free(workbook->formats);
     free(workbook->defined_names);
+    free(workbook->custom_properties);
     free(workbook);
 }
 
@@ -471,7 +494,7 @@ _store_defined_name(lxw_workbook *self, const char *name,
 
     /* Allocate a new defined_name to be added to the linked list of names. */
     defined_name = calloc(1, sizeof(struct lxw_defined_name));
-    RETURN_ON_MEM_ERROR(defined_name, 1);
+    RETURN_ON_MEM_ERROR(defined_name, LXW_ERROR_MEMORY_MALLOC_FAILED);
 
     /* Copy the user input string. */
     strcpy(name_copy, name);
@@ -1328,6 +1351,12 @@ workbook_new_opt(const char *filename, lxw_workbook_options *options)
     workbook->used_xf_formats = lxw_hash_new(128, 1, 0);
     GOTO_LABEL_ON_MEM_ERROR(workbook->used_xf_formats, mem_error);
 
+    /* Add the worksheets list. */
+    workbook->custom_properties =
+        calloc(1, sizeof(struct lxw_custom_properties));
+    GOTO_LABEL_ON_MEM_ERROR(workbook->custom_properties, mem_error);
+    STAILQ_INIT(workbook->custom_properties);
+
     /* Add the default cell format. */
     format = workbook_add_format(workbook);
     GOTO_LABEL_ON_MEM_ERROR(format, mem_error);
@@ -1384,8 +1413,8 @@ workbook_add_worksheet(lxw_workbook *self, const char *sheetname)
 
     /* Check if the worksheet name is already in use. */
     if (workbook_get_worksheet_by_name(self, init_data.name)) {
-        LXW_WARN_FORMAT("workbook_add_worksheet(): worksheet name "
-                        "'%s' already exists.", init_data.name);
+        LXW_WARN_FORMAT2("%s(): worksheet name '%s' already exists.",
+                         __func__, init_data.name);
         goto mem_error;
     }
 
@@ -1625,6 +1654,38 @@ mem_error:
     return -1;
 }
 
+/*
+ * Set the document properties such as Title, Author etc.
+ */
+uint8_t
+workbook_set_custom_property_string(lxw_workbook *self, char *name,
+                                    char *value)
+{
+    lxw_custom_property *custom_property;
+
+    if (!name) {
+        LXW_WARN_FORMAT("%s(): parameter 'name' cannot be NULL.", __func__);
+        return LXW_ERROR_NULL_STRING_IGNORED;
+    }
+
+    if (!value) {
+        LXW_WARN_FORMAT("%s(): parameter 'value' cannot be NULL.", __func__);
+        return LXW_ERROR_NULL_STRING_IGNORED;
+    }
+
+    /* Create a struct to hold the custom property. */
+    custom_property = calloc(1, sizeof(struct lxw_custom_property));
+    RETURN_ON_MEM_ERROR(custom_property, LXW_ERROR_MEMORY_MALLOC_FAILED);
+
+    custom_property->name = lxw_strdup(name);
+    custom_property->value = lxw_strdup(value);
+
+    STAILQ_INSERT_TAIL(self->custom_properties, custom_property,
+                       list_pointers);
+
+    return 0;
+}
+
 lxw_worksheet *
 workbook_get_worksheet_by_name(lxw_workbook *self, char *name)
 {
diff --git a/test/functional/src/test_properties03.c b/test/functional/src/test_properties03.c
new file mode 100644
index 00000000..cd418da0
--- /dev/null
+++ b/test/functional/src/test_properties03.c
@@ -0,0 +1,23 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2015, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_properties03.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+
+    workbook_set_custom_property_string(workbook, "Checked by", "Adam");
+
+    worksheet_set_column(worksheet, 0, 0, 70, NULL);
+    worksheet_write_string(worksheet, CELL("A1"), "Select 'Office Button -> Prepare -> Properties' to see the file properties." , NULL);
+
+    return workbook_close(workbook);
+}
diff --git a/test/functional/test_properties.py b/test/functional/test_properties.py
index 42c9c0c3..e85541db 100644
--- a/test/functional/test_properties.py
+++ b/test/functional/test_properties.py
@@ -18,3 +18,6 @@ class TestCompareXLSXFiles(base_test_class.XLSXBaseTest):
 
     def test_properties02(self):
         self.run_exe_test('test_properties02')
+
+    def test_properties03(self):
+        self.run_exe_test('test_properties03')
diff --git a/test/functional/xlsx_files/properties03.xlsx b/test/functional/xlsx_files/properties03.xlsx
new file mode 100644
index 00000000..391e196e
Binary files /dev/null and b/test/functional/xlsx_files/properties03.xlsx differ