Results of a program conducted to investigate the operation of a medium-speed stationary diesel engine on coal-derived liquid (CDL) fuels are presented. The overall objectives of the program were to evaluate promising techniques for effective utilization of three middle-distillate alternative fuels, namely SRC-II, Exxon Donor Solvent and H-Coal, without adversely affecting engine performance and operation, and to formulate control system algorithms. Investigations of fueling techniques such as on-line blending with diesel fuel, fumigation and the addition of ignition accelerants were conducted as well as investigations of such engine test variables as injection timing and pressure, inlet air temperature and inlet air pressure (i.e., turbocharger boost). In general, it was concluded that diesel engine operation with CDL fuel blends is possible over a wide range of speed and load conditions. Strategies found useful for extending diesel engine operation with CDL fuels include fumigation, inlet air preheat, turbocharger boost and ignition accelerants.