In this paper we define a model, namely the recursive ECATNets (or "RECATNets") allowing the modeling, in a concise way, of the dynamic reconfiguration mechanisms of flexible workflow processes. The descriptive power of this model is also well-suited in modeling collaborative workflows. Recursive ECATNets are based on a sound combination of ECATNets (Extended Concurrent Algebraic Term Nets) and recursive Petri nets. Moreover, since their semantics is defined in the conditional rewriting logic framework, the use of model checking techniques to prove liveness and safety properties becomes possible. For further information, please visit this web site.