Well, MS Excel (97-2003) color palette only supports 56 (0-55 indexed) colors. The palette does not have the color by default, so you have to add it to the color palette using Workbook.ChangePalette() method.
I think you may try the following code:
Workbook workbook = new Workbook(); //Add the color to the Excel palette workbook.ChangePalette(System.Drawing.Color.Lime,55); Worksheet sheet1 = workbook.Worksheets[0]; sheet1.Cells["A4"].Style.ForegroundColor = Color.Lime; sheet1.Cells["A4"].Style.Pattern = BackgroundType.Solid; workbook.Save("d:\\test\\out_book.xls");
Please check the following thread to know more about how to set the foreground , background, font colors etc.