Hello Anand System.Directory.Tree is not a good candidate for serializing directly - as you have found out, one of the constructors - Failed - carries an IOException which cannot be serialized (IOExceptions may contain file handles which are inherently runtime values). Data.Binary is usually the best option for serialization. In your case, you wont be able to make a 1-1 mapping between a runtime DirTree and its on disk representation as you'll have to work out what to do about 'Failed' - maybe you would want to only serialize the good constructors - Dir and File - instead. As you will have to coerce the data type a bit, I'd recommend using Data.Binary to write the serialization, but rather than make instances of Put and Get for DirTree instead give the serialize and deserialize functions characteristic names e.g. serializeGoodTree / deserializeGoodTree. Best wishes Stephen