>This way it works, however the result is different. I will try if it isn't rejected by the WinAPI function.

That's the way it is. It's nothing to do with the API function. The result is different because you take it forward.

Take your sample number:
-2141040952 = "80 62 4E C8"
It will stored in memory/register as "C8 4E 62 80"
You will get the wrong result if you take it forward. So you must take it backward.
cHex = ""
cHex = cHex + Right(Transform(Asc(SubStr(cRes, 4, 1)), "@0"), 2)
cHex = cHex + Right(Transform(Asc(SubStr(cRes, 3, 1)), "@0"), 2)
cHex = cHex + Right(Transform(Asc(SubStr(cRes, 2, 1)), "@0"), 2)
cHex = cHex + Right(Transform(Asc(SubStr(cRes, 1, 1)), "@0"), 2)

And it is the way CPU stored DWORD in memory/register.
Btw, just a curiousity. Why don't you use Transform(-2141040952, '@0'), the result is correct.

>Thanks a lot for you help.
Anytime :)