In this paper, we present our expressive body-gestures animation synthesis model for our Embodied Conversational Agent(ECA) technology. Our implementation builds upon a full body reach model using a hybrid kinematics solution. We describe the full pipeline of our model that starts from a symbolic description of behaviors, to the construction of a set of keyframes till the generation of the whole animation enhanced with expressive qualities. Our approach offers convincing visual quality results obtained with high real-time performance.