Function DiffTemps(Cell1 As Range, Cell2 As Range)
Dim Hr As Long, Mn As Long, Sec As Long
Hr = DateDiff("h", Cell1.Value, Cell2.Value)
Mn = DateDiff("n", Cell1.Value, Cell2.Value) Mod 60
Sec = DateDiff("s", Cell1.Value, Cell2.Value) Mod 60
DiffTemps = Format(Hr, "00") & ":" & Format(Mn, "00") & ":" & Format(Sec, "00")
End Function