The aim of this study was to investigate the mechanical behavior and to develop a micromechanical model for thermoplastic olefin (TPO). The TPO with varying ratios of polypropylene (PP)/rubber/talc were prepared in a twin-screw extruder. The mechanical behavior was studied through a series of tensile tests at different strain rates. Considering TPO as a composite consisting of PP matrix, rubber phase, and talc phase, the effective self-consistent method was used to predict material Young's modulus, and an averaging method was used to predict yield stress. Comparisons between predictions and experiments showed that the models capture the elastic behavior of TPO accurately. POLYM. ENG. SCI., 50:536-542, 2010. (C) 2009 Society of Plastics Engineers