Transformation of Na and K in a lignite was investigated during pyrolysis and gasification in a fixed-bed by using a serial dissolution method with H2O, CH3COONH4, and HCl solutions. The evolution of the fractions of four forms in solid and alkali volatilization during pyrolysis and gasification was determined. The results show that a different mode of occurrence between Na and of K in coal existed. Na in coal can be nearly completely dissolved by H2O, CH3COONH4, and HCl solution. However, K in coal exists almost in the stable forms. Both H2O soluble and CH3COONH4 soluble Na and K fractions decline during pyrolysis and early gasification stage and increase a little with the process of char gasification. The stable form Na in the char produced during pyrolysis is transferred to other forms during char gasification via the pore opening and a series of chemical reactions. Na2SO4 (K2SO4) May play an important role in producing stable forms such as Na2O center dot Al2O3 center dot 2SiO(2) and K2O center dot Al2O3 center dot 2SiO(2) during pyrolysis. The fraction of HCl soluble K increases during pyrolysis but decreases markedly during the early gasification stage.