The kukersite oil obtained industrially in vertical retorts was chemically separated into neutral oil and phenols. Hydrocracking of the fetal oil as well as ifs constituents was performed chemical composition and the properties of the products were determined [1-3]. Besides chemical separation, also distillative fractionation is practised in industry to obtain oils of different properties. This series of works deals with the upgrading of Estonian shale ail fractions obtained in industry using catalytical hydrogenation methods. Shale oil fractions boiling at 180-240 degrees 240-320 degrees and above 320 degrees C - so-called "diesel fraction" fuel oil and heavy fuel oil, respectively, were hydrogenated under various reaction conditions to establish the optimum ones under which the yield of refined oil of desired composition will be maximum. The effect of initial parameters on the yield, composition and properties of products obtained was investigated. The aim of this work was to study the composition of the "diesel fraction" and the effect of hydrogenation on the yield, composition and properties of the products obtained.