Activated carbons were obtained from Turkish coals by one-step steam pyrolysis process. The effect of the water vapor on the yield of the solid, liquid and gas products was studied. The presence of steam during pyrolysis-activation process contributes to distillation of low molecular weight products and reacts with the coal and the volatile products obtained during the pyrolysis. These processes lead to an increase in the yield of liquid and gas products and a decrease in the solid yield. The resulting carbons are determined to have good adsorption characteristics. (C) 2002 Elsevier Science Ltd. All rights reserved.