Coal–derived middle distillate, boiling range 437 to 623°K, was hydrotreated in a fixed bed reactor with a commercial NiO–Mo03/ Al2O3catalyst. The feedstock contained predominantly highly–substituted aromatics. The product heteroatom content and aromaticity decreased with increased process temperature or pressure. Aromaticity was proportional to liquid space velocity. Heteroatonms could be effectively reduced at hydroprocessing conditions of 653°K, 10 MPa, and 2 WHSV. Experimentally–derived cetane number was found to be proportional to product aromaticity. Severe hydroprocessing conditions were required to produce diesel fuel of acceptable cetane number.