Hello,

If you like to use a UDF:

Function charinc(s As String) As String
'Increments a string:
'A will become B
'Z will become AA
'ABCZ will become ABDA
'ZZZ will become AAAA
'Reverse(moc.liborplus.www) v0.10
Dim i As Long
Dim sc As String 'Current char
Dim sp As String 'Prefix
Dim ss As String 'Suffix

sp = s
ss = ""
i = Len(s)
Do While i 0
sc = Right(sp, 1)
If i 1 Then
sp = Left(sp, i - 1)
Else
sp = ""
End If
Select Case sc
Case "A" To "Y"
sc = Chr(Asc(sc) + 1)
Exit Do
Case "Z"
ss = "A" & ss
If i = 1 Then
sp = "A"
sc = ""
Exit Do
End If
Case Else
charinc = CVErr(xlErrValue)
Exit Function
End Select
i = i - 1
Loop
charinc = sp & sc & ss
End Function

Regards,
Bernd