Hi Pratima,
Thanks for your patience.
We are not able to see this issue in the latest version 5.1.x.x. This has been internally fixed in the latest version of Essential Studio 5.1.
As a workaround, you can handle the QueryCellInfo event and apply the FormattedText to the datetime cells in grid. Please refer the below sample that shows this working fine.
http://www.syncfusion.com/Support/user/uploads/GDBG_ExcelExport_6d5da8a4.zip Let me know if you have any other questions.
Have a nice time.
Regards,
Rajagopal