Sub Underline_First_Word()
Dim LR As Integer, FS As Integer
Dim c As Range
LR = Range("A" & Rows.Count).End(xlUp).Row
For Each c In Range("A1:A" & LR)
FS = InStr(1, c, " ")
With c.Characters(Start:=1, Length:=FS - 1).Font
'.Name = "Calibri"
'.FontStyle = "Regular"
'.Size = 11
.Underline = xlUnderlineStyleSingle
'.ThemeColor = xlThemeColorLight1
'.TintAndShade = 0
'.ThemeFont = xlThemeFontMinor
End With
Next c
End Sub