We investigate a formal model for reasoning about real-time object-oriented computations. The model is an extension of CCS with the notion of time, called RtCCS (Real-time Calculus of Communication Systems). It can naturally model real-time concurrent objects as communicating processes and represent the timed properties of objects. We dene two timed equivalences based on CCS's bisimulation and derive algebraic laws for reasoning about real-time processes. The equivalences provide a formal framework for analyzing the behavior and timing of real-time computations. Also, we de ne a sound and complete equational proof system for nite processes. Some examples in RtCCS are shown in order to demonstrate its usefulness. Proceedings of ACM OOPSLA'92