diff --git a/knowledge-base/adding-combobox-to-excel-file-radspreadprocessing.md b/knowledge-base/adding-combobox-to-excel-file-radspreadprocessing.md
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+---
+title: Adding a DropDown/ComboBox to an Excel File Using RadSpreadProcessing
+description: Explains how to add a combo box with specific options to an Excel file using RadSpreadProcessing.
+type: how-to
+page_title: Adding a /ComboBox in Excel Using RadSpreadProcessing
+slug: adding-combobox-to-excel-file-radspreadprocessing
+tags: spread, processing, combobox, excel, listdata, validation, document, dropdown, comma, delimiter
+res_type: kb
+ticketid: 1689410
+---
+
+## Environment
+
+| Version | Product | Author | 
+| ---- | ---- | ---- | 
+| 2025.2.520| RadSpreadProcessing |[Desislava Yordanova](https://www.telerik.com/blogs/author/desislava-yordanova)| 
+
+## Description
+
+Learn how to add a ComboBox with predefined options to an Excel file programmatically using [RadSpreadProcessing]({%slug radspreadprocessing-overview%}). Additionally, the ComboBox should support special characters like commas (or another delimiter) within the options. 
+
+## Solution
+
+To add a DropDown/ComboBox to an Excel file and handle special characters like commas within options, use the [ListDataValidationRule]({%slug radspreadprocessing-features-data-validation%}) with a cell range as the source for the validation. Consider the following sample options: 
+
+* Option 1, Inc.
+* Option 2, Inc.
+* Option 3, Inc.
+
+![Combobox with Specific Options ><](images/adding-combobox-to-excel-file-radspreadprocessing.png)     
+ 
+Below is the sample code:
+
+```csharp
+// Create a workbook
+Workbook workbook = new Workbook();
+Worksheet worksheet = workbook.Worksheets.Add();
+
+// Define the ComboBox options in a cell range
+worksheet.Cells[0, 0].SetValue("ABC, Inc.");
+worksheet.Cells[0, 1].SetValue("123, Inc.");
+worksheet.Cells[0, 2].SetValue("KEF, Inc.");
+worksheet.Cells[0, 3].SetValue("HMS, Inc.");
+
+// Specify the cell where the ComboBox will be applied (e.g., A2)
+CellIndex cellIndex = new CellIndex(1, 0); // A2
+
+// Set up the validation rule with the cell range
+ListDataValidationRuleContext context = new ListDataValidationRuleContext(worksheet, cellIndex);
+context.InputMessageTitle = "Restricted input";
+context.InputMessageContent = "Please select an option from the dropdown.";
+context.ErrorStyle = ErrorStyle.Stop;
+context.ErrorAlertTitle = "Invalid Input";
+context.ErrorAlertContent = "The entered value is not valid. Allowed values are listed in the dropdown.";
+context.Argument1 = "=A1:D1"; // Cell range containing the options
+ListDataValidationRule rule = new ListDataValidationRule(context);
+
+// Apply the validation rule to the specified cell
+worksheet.Cells[cellIndex].SetDataValidationRule(rule);
+
+// Save the workbook to a file
+string outputFilePath = "ComboBoxExample.xlsx";
+File.Delete(outputFilePath);
+using (FileStream stream = new FileStream(outputFilePath, FileMode.Create))
+{
+    XlsxFormatProvider formatProvider = new XlsxFormatProvider();
+    formatProvider.Export(workbook, stream, TimeSpan.FromSeconds(60));
+}
+
+// Open the generated file
+Process.Start(new ProcessStartInfo() { FileName = outputFilePath, UseShellExecute = true });
+```
+
+### Key Points
+- Use a cell range to define options if the values include commas or other special characters that are not allowed out-of-the-box.
+- The `Argument1` property supports referencing a range of cells (e.g., `=A1:D1`) as dropdown options.
+
+## See Also
+
+- [RadSpreadProcessing Overview]({%slug radspreadprocessing-overview%})
+- [List Rule Data Validation]({%slug radspreadprocessing-features-data-validation%}#list-rule)
+- [Setting the Culture]({%slug radspreadprocessing-features-setting-the-culture%}) 
diff --git a/knowledge-base/images/adding-combobox-to-excel-file-radspreadprocessing.png b/knowledge-base/images/adding-combobox-to-excel-file-radspreadprocessing.png
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diff --git a/libraries/radspreadprocessing/features/data-validation.md b/libraries/radspreadprocessing/features/data-validation.md
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+++ b/libraries/radspreadprocessing/features/data-validation.md
@@ -376,4 +376,5 @@ __Example 11__ demonstrates how to evaluate a rule using the __Evaluate()__ meth
 ## See Also
 
 * [Protection]({%slug radspreadprocessing-features-protection-workbook%})
-* [Formulas]({%slug radspreadprocessing-features-formulas-general-information%})
\ No newline at end of file
+* [Formulas]({%slug radspreadprocessing-features-formulas-general-information%})
+* [Adding a ComboBox to an Excel File Using RadSpreadProcessing]({%slug adding-combobox-to-excel-file-radspreadprocessing%})
\ No newline at end of file