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The present work aims to study the organic chemistry, the generation and maturation of the hydrocarbons encountered at Abu Roash Formation, Wadi El Rayan oil field. The analysis of source rocks indicates the presence of two organic facies. The first is characterized by high total organic carbon of 0.93-3.39%, strongly oil-prone (Type II), and good potential for oil generation (pyrolysis S2 yields 4.54-23.26 mg HC/g rock and HI 488-705 mg HC/g TOC). The second attains good range of organic carbon from 0.90% to 1.57%, which is a mixed oil and gas (Type II-Type III) of fair hydrocarbon generation (pyrolysis S2 yield of 1.98-5.33 mg HC/g). The kerogen type consists of unstructured lipids and some terrestrial material. Plot of Pr/n-C17 versus Ph/n-C18 indicates that the crude oil was derived from mixed source rock, while the maturity profile assigns oil windows (0.6 R-o%) matching topmost of Abu Roash G Member.