OCX files are the result of programming (typically with active x). Ultimatly, unless you have the entire project (source code) they are not going to be much use to you. Technically your answer is Microsoft Visual Studio will open these files. But these files are for reference and support for programming languages (VB) and dont really "open" in the way that you may be thinking. What is the result you are trying to accomplish? Maybe there is another way.