The objective of this research is to study the effect and mechanism of FeCO3-based catalytic gasification of a low-sulfur sub-bituminous Wyodak coal from the Powder River Basin (PRB) of Wyoming. The catalytic effect was evaluated by comparing the gas compositions and carbon conversion kinetics with and without of FeCO3, which was realized by gasifying the coal with a fixed-bed laboratory gasifier within steam environment at atmospheric pressure. X-ray diffraction (XRD) and Mossbauer spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were used to study the involved catalytic mechanism through characterization of the iron species and oxidation states of the catalyst and the composition of tar released during pyrolysis. Experimental results show that the catalyst is active in both pyrolysis and gasification steps, and can increase carbon conversion rate and reduce the activation energy of coal gasification. In addition, its oxidation states including magnetite (Fe3O4), wustite (FeO), and metallic iron, change with gasification condition. The research indicates that FeCO3 is a promising catalyst for coal gasification. Published by Elsevier B.V.