<asp:GridView ID=”gridview1” runat=”server” SkinID=”GridTheme” Width=”100%” AutoGenerateColumns=”False” >
<Columns>
<asp:BoundField HeaderText=”Member Since” DataField=”TimeStamp”
DataFormatString=”{0:M-dd-yyyy}” />
</Columns></asp:GridView>
from : http://www.ganshani.com/2008/05/06/date-format-in-gridview-aspnet-20/