>I've written an OLE automation server with vfp 6 SP3 and my coleague need to access it from his application written in C (not C++).
>Is there a way to do this ?

COM is language-independent, so C will work. Giving step-by-step instructions on how to is a little unwieldy for this forum, but any good COM book like Inside COM will show you how it's done. In a nutshell:

CoInitialize()
CoCreateInstance()
QueryInterface()
Call the method

You don't need C++ for that.