Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. As a means to achieve repeated use of catalysts, four different ash-free coals (AFCs) containing less than 0.2 wt% ash are produced in this work. Steam gasification of ash-free coals (AFCs) and their parent raw coals of various ranks ranging from lignite (Eco) to coking coal (Posco) is performed in a fixed bed reactor at 700-900 degrees C. Regardless of the rank of the parent raw coals, all the AFCs behave like a highly carbonized coal such that their gasification rate are similarly slow and they exhibit relatively low H-2/CO ratio. The steam gasification and associated CO to CO2 conversion of the AFCs are, however, significantly enhanced by K2CO3, resulting in the higher H-2/CO and CO2/CO molar ratio. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.