I cannot reproduce the problem.
I entered some times like 4:15, 18:30 into a range of cells, selected all
the cells and gave then the custom format hhmm
As soon as I hit OK to close the format dialog they displayed as 0415, 1830
etc
I did this in both XL 2003 and 2007
Can you give more details?
Can you use F9 to force the change?
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Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
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"Sagebrook" wrote in message
...
I have custom formated several cells to hhmm. Unfortunately, all the
times
have remained unchanged. They will convert to the wanted format if I
double-click on the cell or hit F2 and enter. This is fine if there are
only
a few cells, but I have hundreds...

Is there a way to force all the cells to convert?