Software systems have become increasingly distributed, dynamic and mobile. The complex state and dynamic interfaces of software components and their concurrent interactions provide challenging research issues in system specification and design. An effective combination of structured state-based formalism and dynamic action-based calculus may be a good solution for modeling complex distributed mobile systems. In this paper, we investigate the semantic links between Object-Z and π calculus and consequently introduce a powerful specification technique PiOZ that brings the strengths of the two together. The operational semantics of PiOZ integrates state transition semantics of Object- Z and π-calculus reduction rules. The typing rules of PiOZ are developed and reasoning of a system property is presented.