Waste samples of polyethylene and polystyrene were cracked thermally or in the presence of catalyst and hydrogen in closed autoclaves. The obtained products were submitted to analysis, unsaturated hydrocarbons in gasoline and diesel fuel range boiling were hydrogenated over platinum catalyst. It was stated that the optimum thermal cracking temperature of waste polyolefines is 410-430 degreesC, in the case of catalytic process lower temperature, ca. 390 degreesC, can be used, with reaction time ca. 1.5 an hour. More than 90% yield of gas and liquid fractions with b.p. < 360C was attained. The dependencies between process parameters, feed composition and product yield as well as composition of the obtained fuel fractions were found. On the basis of the obtained results hypothetical continuous process of waste plastics processing for engine fuel production was presented.