Samples of El-Lajjun oil shale were thermally decomposed in a laboratory retort system under a slow heating rate (0.07 K/s) up to a maximum temperature of 698-773 K. After decomposition, 0.02 kg of spent shale was extracted by chloroform in a Soxhlet extraction unit for 2 h to investigate the ultimate amount of shale oil that could be produced. The retorting results indicate an increase in the oil yields from 3.24% to 9.77% of oil shale feed with retorting temperature, while the extraction results show a decrease in oil yields from 8.10% to 3.32% of spent shale. The analysis of the data according to the global first-order model for isothermal and nonisothermal conditions shows kinetic parameters close to those reported in literature.