The method of using room temperature Mossbauer spectros copy were applied to identify the iron species in kerogen is illustrated for a series of 22 subsurface core samples from three oil fields : July, GS315 and Esh El-Melaha in the Gulf of Suez region, Egypt. The Mossbauer spectra of kerogen showed only two central quadrupole doublets that would be attributed to the presence of iron in pyrite/Fe2+ (lowspin) and in carbonates possible ankerite/Fe2+ (highspin). Possible explanation for the presence of ankerite is discussed and it is suggested that a high level of maturation is the most likely reason. This suggestion is corroborated by data of the total organic carbon and the vitrinite reflectance which is available for all the samples studied.