Kinetic tests on pyrolysis of the mixture of waste automobile lubricating oil (WALO) and polystyrene (PS) were carried out with a thermogravimetric analysis (TGA) technique at a heating rate of 0.5 degrees C/min, 1.0 degrees C/min and 2.0 degrees C/min in a stirred batch reactor. WALO and PS were mainly decomposed 400-455 degrees C and 370-410 degrees C, respectively. The mixture of WALO and PS, however, was decomposed between 355 degrees C and 470 degrees C, and decomposition proceeded in two broad steps. The apparent activation energies for the pyrolysis of WALO/PS mixture were in the range of 176 kJ mol(-1)-369 kJ mol(-1) at various conversions of 1-100%. The effect of heating rate on the product distribution was studied. The carbon number distribution of the produced oil shifted slightly to light hydrocarbons with a decrease in heating rate. The selectivity of hydrocarbons corresponding to the styrene monomer was high for the pyrolysis of the WALO/PS mixture. (C) 2012 Elsevier Ltd. All rights reserved.