Dim Lig As Long, Col As Long
Lig = Range("A" & Rows.Count).End(xlUp).Row
Col = Cells(Lig, Columns.Count).End(xlToLeft).Column + 1
If Col > 26 Then
Lig = Lig + 1
Col = 1
End If
If Range("A1").Value = "" Then
Range("A1").Value = "toto"
Else
Cells(Lig, Col).Value = "toto"
End If