Sub TranslateDocIntoDocx()
  Dim objWordApplication As New Word.Application
  Dim objWordDocument As Word.Document
  Dim strFile As String
  Dim strFolder As String

  strFolder = "E:\Temp\"
  strFile = Dir(strFolder & "*.doc", vbNormal)

  While strFile <> ""
    With objWordApplication
      Set objWordDocument = .Documents.Open(FileName:=strFolder &strFile, AddToRecentFiles:=False, ReadOnly:=True, Visible:=False)

      With objWordDocument
        .SaveAs FileName:=strFolder & Replace(strFile, "doc", "docx"), FileFormat:=16
        .Close
      End With
    End With
    strFile = Dir()
  Wend

  Set objWordDocument = Nothing
  Set objWordApplication = Nothing
End Sub