Abstract: The temperature programmed steam gasification (TPSG) of lignite from Baganuur, Mongolia was studied in a micro fixed-bed reactor with chromatography. The formation rate of H₂,CO and CO₂ during the TPSG were examined using the lignite samples pretreated by washing with HCl and NH₄OH solution or NaOH solution following the washing by HCl solution. All the samples were pyrolyzed at 650 ℃. The results show that a significant difference in the formation rate of gas components is presented for the tested lignite samples. The inherent minerals in the Baganuur lignite can accelerate the generation rate of H₂ and CO₂, but simultaneously reduce the generation rate of CO, which could manufacture a high H₂/CO mol ratio syngas. Also, some inherent minerals in the Baganuur lignite can remarkably enhance the steam gasification rate, which results in an drop of initial steam gasification reaction temperature by over 100 ℃. It is speculated that the enhanced steam gasification reaction of Baganuur lignite could be attributed to the effect of some inherent minerals on the water-gas shift reaction. Finally, the possible in-situ catalytic mechanism of inherent minerals in Baganuur lignite to the steam gasification reaction is discussed.