Many thanks for your reply
I have a seperate routine which defines the columns of the grid
for the relevant column
DataGridTableStyle ItemList= new DataGridTableStyle();
ItemList.MappingName="TblEventitems";
DataGridTextBoxColumn Col3=new DataGridTextBoxColumn ();
Col3.Headertext="Start";
Col3.MappingName="EIStart";
Col3.Format="HH:mm";
Col3.NullText="00:00";
Col3.Width=50;
Col3.Alignment=HorixontalAlignment.Center;
ItemList.GridColumnStyles.Add(Col3);
DataGrid1.TableStyles.Add(ItemList);
other columns save OK even for the same record but the time remains 00:00 I
have tried removing the NullText format