Bonjour,
Les noms en colonne A de la feuille "Feuil1" :
Sub Test()
Dim Plage As Range
Dim Cel As Range
With Worksheets("Feuil1"): Set Plage = .Range(.Cells(1, 1), .Cells(.Rows.Count, 1).End(xlUp)): End With
For Each Cel In Plage
If UCase(Cel.Offset(, 1).Value) = "X" Then Cel.Offset(, 1).Value = Cel.Value
Next Cel
End Sub