Thanks redycc, but IdFTP definitly doesn't work with Mac OS X.
Note that the IdHttp component has also some problems with Mac OS X. I use it, but I have to free it then recreate it before each connexion, otherwise an exception occurs.
Indy is very unstable for this platform. Moreover, it's annoying, but IdFTP component triggers exception on success. I can't understand this behavior (neither agree with it).
I still use it only for windows/delphi environment.
André.