In this study, kinetics parameters of combustion reaction of Seyitomer and Beypazari oil shales were determined using Weijdema's model of reaction kinetics. The analysis of reaction kinetics experiments showed two different reaction regions at combustion of Beypazari oil shale sample. Only one reaction region was observed at combustion of Seyitomer oil shale. CO2/CO ratios increased gradually at low and medium temperatures and stabilized at high temperatures, especially after complete combustion. A decrease in the H/C ratio with the increasing temperature was observed. No relationship between activation energies of different oil shale types was observed.