Basically my MVC 3 application generates an Excel file upon user request. My problem, one of the columns contains data like the following "01/2015"... this represents a work-week of a year. This property is a string value in my application and displays perfectly on the screen within the application but once in Excel file, 01/2015 displays as Jan-2015. So workweeks 01 - 12 display as months Jan - Dec. I cannot use a macro as this file will be generated new each time from the MVC 3 application. I being advised to create an exe file, using this exe file to locate the excel and run it allowing the exe to alter the data or column . Unfortunately I have no idea how or where to start on that option ? Any ideas ?