The oil shale deposits in Turkey are widely distributed in middle and western Anatolia. Turkish oil shales are of Palaeocene-Eocene and middle upper Miocene age. Current reserves of oil shales are approximately 2,220 million tons (total reserve) and mainly are located in Himmetoglu, Seyitomer, Beypazari, and Hatildag deposits. Some petrological, geochemical, Fisher Assay, and fluidized combustion tests are performed for these oil shale fields, and it was concluded that Himmetoglu oil shale is the most appropriate for domestic and industrial utilization. On the other hand, differential scanning calorimetry-pressurized (DSC-PDSC) and thermogravimetry (TG/DTG) experiments were performed with these oil shale samples. In pyrolysis experiments, oil shale samples showed one exothermic effect at each total pressure studied. A general trend to decreasing in activation energy with increasing pressure in pyrolysis, and increasing in activation energy with increasing pressure was observed in combustion experiments.