I tried

MsgBox myChart.SeriesCollection(1).XValues

MsgBox myChart.SeriesCollection(1).XValues.Address

MsgBox myChart.SeriesCollection(1).XValues.Value

They don't work. Here the of code:

Sub Macro4_2()

Dim rArea As Range, rXValues As Range, rYValues As Range
Dim c As Variant
Dim i As Integer
Dim iNseries As Integer
Dim chtmyChart As Chart
Dim sSTR As String

Set rArea = Application.InputBox(prompt:="Select range:", Type:=8)
Set rXValues = Application.InputBox(prompt:="Select XValues:", Type:=8)
Set rYValues = Application.InputBox(prompt:="Select YValues:", Type:=8)

iNseries = rArea.Rows.Count - 1
Set chtmyChart = Charts.Add

With chtmyChart
For i = 1 To iNseries
.SeriesCollection.NewSeries
Next
.Name = "Pippo"
i = 1
For Each c In .SeriesCollection
sSTR = "=Foglio1!" & rArea.Offset(i - 1, 0).Resize(1,
rArea.Columns.Count).Address(ReferenceStyle:=xlR1C 1)
Rem c.Values = "=Foglio1!$C$4:$L$4"

Rem c.Values = sSTR
c.Name = "=Foglio1!" & rYValues(i - 1).Address(ReferenceStyle:=xlR1C1)
c.XValues = rXValues.Address
i = i + 1
Rem MsgBox "LABEL: " & sYValues(i).Address & "SERIE: " & sSTR & ""
Next
.ChartType = xlSurface
End With

all things go fine <<

MsgBox chtmyChart.SeriesCollection(1).XValues

macro stops <<

End Sub