Hi Xabi
>Hi,
>DLL com objects, have they its own memory space?

DLL COM runs on the creator memory space if you want them to run in a separate memory space then you need to create a COM+ application where you add your COM Dll

>Can they be deployed as DCOM objects?

YES

>What differences are between multithread and non multithread DLL com objects?

in Single threaded Dll's only 1 request can be processed so if you have 2 clients calling your dll the second one will wait until the first end's the call.
in Multithreaded you can have as many clients calling you dll all the request are processed simultaneous.

>
>Thanks in advance,
>Xabi