The last code you wrote throws out a few errors when I test it in a
new workbook.

It doesn't accept the correct time even if typed in, if I copy a whole
range in it shows error 13 - Type mismatch on "j = CLng(d)" and when
data is deleted it shows the invalid data msgbox.

However with the small tweak you suggested to the original code it
seems to work perfectly! I tested all above issues including the text
validation and everything seems to work as it should. Extremely happy
with it - I was beginning to lose hope!

So thank you very much again! Your help is very much appreciated.

Here is the winning code:

Application.EnableEvents = False

Dim C22ValRange As Range
Dim DataOK As Boolean
Dim msg As String
Dim rCell As Range
Dim sCell As Range
Dim endCell As Range
Dim cellRow As Long

Dim Times(25) As Date

Times(1) = 0 '12AM
Times(2) = 4.16666666666666E-02 '1AM
Times(3) = 0.083333333 '2AM
Times(4) = 0.125 '3AM
Times(5) = 0.166666666666666 '4AM
Times(6) = 0.208333333333333 '5AM
Times(7) = 0.25 '6AM
Times(8) = 0.291666666666666 '7AM
Times(9) = 0.333333333333333 '8AM
Times(10) = 0.375 '9AM
Times(11) = 0.416666666666666 '10AM
Times(12) = 0.458333333333333 '11AM
Times(13) = 0.5 '12PM
Times(14) = 0.541666666666666 '1PM
Times(15) = 0.583333333333333 '2PM
Times(16) = 0.625 '3PM
Times(17) = 0.666666666666666 '4PM
Times(18) = 0.708333333333333 '5PM
Times(19) = 0.75 '6PM
Times(20) = 0.791666666666666 '7PM
Times(21) = 0.833333333333333 '8PM
Times(22) = 0.875 '9PM
Times(23) = 0.916666666666666 '10PM
Times(24) = 0.958333333333333 '11PM
Times(25) = 0.999999999999999

Set C22ValRange = Range("C11:C34")

For Each rCell In C22ValRange
For Each sCell In Target
If rCell.Address = sCell.Address Then
MsgBox "Cell " & rCell.Address
cellRow = rCell.Row - 10
MsgBox cellRow
If rCell.Value = Times(cellRow) And rCell.Value <
Times(cellRow + 1) Then
Debug.Print rCell.Value
MsgBox "Valid Time " & rCell.Address
Else
MsgBox "Invalid Time " & rCell.Address
Debug.Print rCell.Value
rCell = ""
End If
End If
Next sCell
Next rCell
Application.EnableEvents = True