This will do the axis titles for 2d charts assuming there is a series on the secondary axis.
Sub x()
With ActiveChart
With .Axes(xlValue, xlPrimary)
.HasTitle = True
.AxisTitle.Text = "Primary Y axis"
End With
With .Axes(xlCategory, xlPrimary)
.HasTitle = True
.AxisTitle.Text = "Primary X axis"
End With
With .Axes(xlValue, xlSecondary)
.HasTitle = True
.AxisTitle.Text = "Secondary Y axis"
End With
With .Axes(xlCategory, xlSecondary)
.HasTitle = True
.AxisTitle.Text = "Secondary X axis"
End With
End With
End Sub