Co-pyrolytic behaviours of plastic/biomass mixtures were investigated using a thermogravimetric analyser under heating rate of 20 degrees C/min from room temperature to 650 degrees C. The biomass sample selected was Chinese pine wood sawdust, while high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene were selected as plastic samples. Results obtained from this comprehensive investigation indicated that plastic was decomposed in the temperature range 438-521 degrees C, while the thermal degradation temperature of biomass is 292-480 degrees C. The difference of weight loss (Delta W) between experimental and theoretical ones, calculated as algebraic sums of those from each separated component, is about 6-12% at 530-650 degrees C. These experimental results indicate a significant synergistic effect during plastic and biomass co-pyrolysis at the high temperature region. In addition, a kinetic analysis was performed to fit thermogravimetric data, the global processes being considered as one to three consecutive first order reactions. A reasonable fit to the experimental data was obtained for all materials and their blends. (C) 2006 Elsevier B.V. All rights reserved.