Abstract The paper was aimed at evaluating the efficiency of impregnation of composite catalysts consisting of K, Na and/or Ca on a coal surface and the impact of composition of two-component catalysts and amount of three-component catalysts on the steam gasification reactions of coal. To this end, detailed analysis of the prepared samples was performed, and isothermal gasification measurements at various temperatures were carried out. The measurements enabled the examination of carbon conversion reaction and formation reactions of CO and H2 using reactivity indicators and kinetic parameters. The most efficient composites were 3 wt% of K/Na/Ca and 2 wt% of K/Na, although impregnation of Na was the least efficient, wherein the catalytic effect was observed only at low temperatures. In turn, higher amounts of three-component catalysts were catalytically inactive. Therefore, catalyst composition was more crucial than its amount or impregnation efficiency.