In this paper, we present a real time animator for dynamical systems that can be modeled as hybrid automata i.e. standard finite automata extended with differential equations. We describe its semantic foundation and its implementation in Java and C using CVODE, a software package for solving ordinary differential equations. We show how the animator is interfaced with the Uppaal tool to demonstrate the real time behavior of dynamical systems under the control of discrete components described as timed automata. 1 Introduction Uppaal is a software tool for modeling, simulation and verification of real time systems that can be described as timed automata. In recent years, it has been applied in a number of case studies [4, 5, 6, 7, 8], which demonstrates the potential application areas of the tool. It suits best the class of systems that contain only discrete components with real time clocks. But it can not handle hybrid systems, which has been a serious restriction on many industrial ap...