Hi Tom If you are interfacing with non-Haskell binary objects - you will want binary parsing / writing rather than simple serialization as the format will be determined by the foreign objects. You can still use Data.Binary (indeed its probably the best choice), but you will want to use the modules Data.Binary.Get and Data.Binary.Put directly and probably avoid the Binary class as it is specialized to serializing values for Haskell only. There are probably quite a few libraries on Hackage that you can look at for examples, though there might be more packages that supply parsers only and don't do writing, e.g: http://hackage.haskell.org/package/pecoff (Parser only) There will be more among the packages this list that directly depend on Binary: http://bifunctor.homelinux.net/~roel/cgi-bin/hackage-scripts/revdeps/binary-... Best wishes Stephen