In this research, the effect of heating rate and different clay concentrations on heavy oil combustion was investigated by thermogravimetry (TG-DTG). In TG-DTG experiments, two main distinct reaction regions were identified in all of the crude oil + limestone mixtures; known as low temperature oxidation (LTO) and high temperature oxidation (HTO) respectively. It was observed that addition of clay to porous matrix (limestone + heavy oil) significantly affected the thermal characteristics and kinetics of crude oil. It was also observed that heating rate affected the reaction region intervals, peak and burn-out temperatures. Kinetic analysis of the samples was determined and it was observed that activation energies generated for the high temperature oxidation region for crude oil and crude oil/clay mixtures are in the range of 48.5-151 kimol(-1) at three different heating rates (C) 2011 Elsevier B.V. All rights reserved.