In this paper the influence of dispersed catalysts obtained in situ based on various metals (Mo, Ni, Fe, Co) has been studied on the yield and properties of liquid products in a slurry-reactor at a temperature of 425°C and a pressure of 20 MPa. The most active catalytic compositions for the process of catalytic steam cracking of oil (Mo and Mo-Fe) were selected. In the presence of dispersed Mo and Mo-Fe catalysts the samples of the semisynthetic oils were produced. In the rectification process the gasoline, diesel, oil and residual fractions were allocated. The selected fractions were analyzed by physicochemical methods for a wide range of performance in comparison with the initial heavy oil. The efficiency of the use of Mo-Fe catalysts for obtaining semisynthetic oil with an increased content of light fractions (i.b.p.- 360ºС) during the catalytic steam cracking of heavy oil was shown.