The influence of a group of metal oxide, hydroxide and chloride catalysts on the yields of liquefied products has been identified. The results of hydrogenation experiments performed with varying coal to catalyst ratio for a slurry of lignite coal in toluene demonstrated that metal loadings even as low as 1% proved effective for enhancement of yields. Among the catalysts employed, halide catalysts proved to be the most effective in terms of high yields of desirable liquefied products. (c) 2007 Elsevier Ltd. All rights reserved.