Hi Nandkishor, 

This is a feature that we're currently looking to add to the xamWebGrid in a future release. However, until then, you can handle the Grid's CellControlAttached event, and use the ToolTipService attached property to add a tooltip to a  cell. 

Note: if you take this approach, it is every important, to set the Tooltip to null, for cells you aren't adding a tooltip to, as CellControl's get recycled, which means if you don't clear out the value, it could display a dead value. 

void DataGrid1_CellControlAttached(object sender, CellControlAttachedEventArgs e)

            {

                  if(e.Cell.Column.Key == "Title")

                        ToolTipService.SetToolTip(e.Cell.Control, e.Cell.Row.Data);

                  else

                        ToolTipService.SetToolTip(e.Cell.Control, null);

            }

Hope this helps, 

-SteveZ