As part of a program for the evaluation of coal liquefaction, supported by the French government and the European Community between 1980 and 1990, our Institute has developed a synthetic catalyst. We first consider the approach that led us to the selection of iron-based solids in the form of dispersed disposable catalysts, as a convenient solution to the improvement of;coal liquefaction efficiency. This choice implies the catalysts possess some specific properties which are detailed in the light of experimental and operational evidences. Several methods for the production of highly divided solids have been tested experimentally. The most promising phases were obtained through hydrolysis of volatile iron compounds in a hydrogen-oxygen flame. We present the characterization of these catalyst precursors; their interaction with the reacting medium, resulting in the formation of the actual active phase, is discussed. Finally, an evaluationof the performances of aerosol iron-based catalyst in coal liquefaction is presented.