A special thermogravimetric analysis (TGA) method was developed to quantify the mass percentage of wood flour and polypropylene copolymer in wood plastic composites (WPC). Step separation of TGA curves was used for quantitative analysis. Four thermal degradation steps were identified and allocated to the wood and polymer fractions, respectively, based on the TGA curves for the individual components of WPC. TGA curves of the additives, maleic-anhydride-modified polypropylene and lubricant, were assigned to the polymer fraction. The heating rate was fitted to the thermal degradation of the single components by using dynamic and isothermal segments. The results show that the wood flour and polymer fractions can be quantified by TGA. For the final developed method, the deviations from the expected wood flour and polymer fractions were not exceeding 5.4% and 14.3%, respectively. Amounts of wood flour and polymer of WPC with known formulation can be rapidly quantified using TGA, therefore, this method is a useful tool for production control. (C) 2012 Elsevier B.V. All rights reserved.