Abstract: The invention relates to a process for the exploitation of oil shales wherein the two main constituents thereof, organic and inorganic moieties, are transformed into valuable products. It was found that oil shales which possess a high amount of inorganic constituents, as well as the mineral part resulted from the combustion of oil shales, have a catalytic effect on the cracking of a heavy fraction of fuel, producing valuable fractions of hydrocarbon fuel. According to the process, a mixture of oil shales which possess a low portion of organic moiety, is cracked at a temperature in the range of 350.degree. to 600.degree. C. with a fraction of heavy fuel having a boiling point of above 350.degree. C. From the gases going out from the cracking reactor, hydrocarbon fuel having a boiling point of up to 350.degree. C. is recovered. The residue resulted in said cracking is useful as a raw material in the chemical industry.