In the Eskisehir Basin, western Turkey, oil shale occurs in alternation with claystone, siltstone, conglomerate and coal (lignite) seams in lacustrine deposits of Early-Middle Miocene age. The thickness of oil shale seams drilled during the study varies between 20 and 30 m. Organic geochemical features of the shale were evaluated using TOC, pyrolysis, GC and GC-MS analyses. The Eskisehir oil shale is characterized by very high TOC contents (6.32-37.15 wt%), Hydrogen Index (HI = 392-777 mg HC/g TOC), Potential Yield (PY = 35.50-159.32 mg HC/g rock) and very low Oxygen Index (OI = 13-92 nig CO2/g TOC) values. Organic matter in the studied oil shale is of Type II kerogen and shows S-2/S-3 ratio values between 5.49 and 56.79 and low T-max (421-435 degrees C) and PI(0.01-0.05) values. Low Pr/Ph ratio of oil shale (0.17-0.96) is indicative of anoxic conditions. Dominant steranes are either C-27 or C-28. Normal steranes are more abundant than iso- and diasteranes and diasterane abundances as well as 20S/(20S + 20R) and beta beta/(beta beta + alpha alpha) sterane ratios are low. While oil shale samples in general have low tricyclic terpane (C-19-C-22) abundance, their C-30 (R + S) tricyclic terpane content is high. For all the oil shale samples studied C-29/C-30 hopane, C31R homohopane/hopane and moretane/hopane ratios are high and Ts/(Ts + Tm) and C20TS/(C20Ts + C29H) ratios are low. 225 homohopanes are recorded in lower quantities in comparison to 22R epimers and the 22S/(22S + 22R) homohopane ratio is low.