Private Sub CommandButton1_Click()
Dim Tableau As Variant, I As Long
Tableau = Range("A1:B" & Cells(Rows.Count, 1).End(xlUp).Row)
For I = 2 To UBound(Tableau, 1)
Tableau(I, 2) = "Mon_Texte"
Next I
Range("A1").Resize(UBound(Tableau, 1), UBound(Tableau, 2)) = Tableau
End Sub