Potassium-catalyzed steam gasification of petroleum coke for H-2 production was performed using a laboratory fixed-bed reaction system with an on-line quadruple mass spectrometer. The gasification reactivity, gasification selectivity and gas release for the catalytic gasification were investigated, compared with the non-catalytic gasification. The catalytic gasification could not only effectively promote these reactions (the water-carbon reaction, the water-gas shift reaction and the methane-steam reforming reaction), but also elevate greatly the gasification selectivity towards CO2 (a high gasification selectivity towards CO2 meant a high H-2 production). A quantitative calculation method for the gasification selectivity towards CO and CO2 was proposed to further understand the catalytic behaviors of catalysts. In the case of catalytic gasification, the gasification temperature had opposite effects on the gasification reactivity and the gasification selectivity towards CO2, suggesting that there existed an optimum gasification temperature (about 750 degrees C) for H-2 production from the potassium-catalyzed steam gasification of petroleum coke. In addition, petroleum coke could be feasibly utilized as the feedstocks for the catalytic steam gasification to produce gases with high H-2 (55.5-60.4%) and virtually no CH4 (below 0.1%). (C) 2010 Elsevier B.V. All rights reserved.