Hi!

Here's one way but it isn't as automatic as you're
thinking.

First you have to have a starting time to base a formula
on. You could enter a date-time stamp in a cell. Say for
example that cell is A1. You enter:

1/17/2004 2:00 PM

Now select the EMPTY cells that you want to highlight.
Goto FormatConditional Formatting.
From the dropdown select Formula IS.
Enter this formula in the box:

=NOW()$A$1+1

Click the Format button and select the style(s) that you
want then OK out.

Now the caveat: This will not automatically change the
highlight at EXACTLY the time intended because the formula
is NOT DIRECTLY LINKED TO YOUR SYSTEM CLOCK.

The NOW() function is volatile, meaning it will update
EACH time there is a workbook calculation. So, on the
first calculation after 24 hours have passed the empty
cells will highlight.

To do EXACTY what you want would require VBA.

Biff

-----Original Message-----
How can empty cells automatically highlight after 24
hours?
.