Results of investigations carried out in a process development unit on hydrotreating of middle distillates from destructive processing of Russian petroleum heavy fractions are discussed. Raw distillates are characterized by considerably higher nitrogen and aromatics contents than corresponding straight-run oil fractions and show clear instability in the colour and a tendency to form sediments. Hydrotreating experiments have been performed over various available commercial catalysts: CoMo, NiMo and NiW, at changing conditions of pressure and LHSV. The use of a new-generation, high-activity NiMo catalyst enables researchers to obtain, under reasonable process conditions, good-quality, stable products showing low nitrogen and sulphur contents. They may be used as components of domestic fuel oil or even of diesel fuel meeting requirements of European directives for 2005. (C) 2004 Elsevier B.V. All rights reserved.