Sub Macro1()
Dim lngRowEnd As Long
Dim rngCell As Range, _
rngMyDataSet As Range
lngRowEnd = Cells(Rows.Count, "H").End(xlUp).Row
Set rngMyDataSet = Range("H2:H" & lngRowEnd)
Application.ScreenUpdating = False
For Each rngCell In rngMyDataSet
If Len(rngCell.Value) = 0 Then
rngCell.Value = "I found it"
Exit For
End If
Next rngCell
Application.ScreenUpdating = True
End Sub