diff --git a/views_data_export_phpexcel.api.php b/views_data_export_phpexcel.api.php
new file mode 100644
index 0000000..01b6b1e
--- /dev/null
+++ b/views_data_export_phpexcel.api.php
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * @file
+ *   API documentation for Views Data Export PHPExcel module.
+ */
+
+/**
+ * Alter the PHPExcel object before the report is generated.
+ *
+ * @param object $objPHPExcel
+ *   The PHPExcel object.
+ * @param object $view
+ *   The view object.
+ * @param array $complete_array
+ *   The processed array of values to ad to the Excel object
+ */
+function hook_views_data_export_phpexcel_alter($objPHPExcel, $view, $complete_array) {
+  // Let's change the numeric format for some cells.
+  $objPHPExcel->getActiveSheet()->getStyle('A1:AZ3')
+    ->getNumberFormat()
+    ->setFormatCode( '0000000000' );
+}
diff --git a/views_data_export_phpexcel.theme.inc b/views_data_export_phpexcel.theme.inc
index d37b2e8..7f16491 100644
--- a/views_data_export_phpexcel.theme.inc
+++ b/views_data_export_phpexcel.theme.inc
@@ -25,6 +25,10 @@ function theme_views_data_export_xlsx_body(&$vars) {
   // Create PHPExcel spreadsheet and add rows to it.
   $objPHPExcel = new PHPExcel();
   $objPHPExcel->setActiveSheetIndex(0);
+
+  // Invoke alter hook to modify the exported data.
+  drupal_alter('views_data_export_phpexcel', $objPHPExcel, $vars['view'], $complete_array);
+
   $objPHPExcel->getActiveSheet()->fromArray($complete_array);
 
   $excel_type = 'excel2007';