The decompiler requires the latest version of IDA Pro. While it may work with older versions (we try to ensure compatibility with a couple of previous versions), the best results are obtained with the latest version: first, IDA analyses files better; second, the decompiler can use additional available functionality.
The decompiler runs only under MS Windows. It can decompile programs for other operating systems, provided they have been built using GCC/Visual Studo/Borland compilers. Note: with the upcoming IDA Qt, the decompiler will be available on other platforms too.
The GUI version of IDA is required for the interactive operation. For the text mode version, only the batch operation is supported.