This work mainly evaluated the feasibility of preparation of activated carbon from the residue of plasma pyrolysis of coal from Karamay, China, by steam activation. The demineralization was brought in to analyze the effect of ash content on the porosity development of activated carbon. The maximum Brunner-Emmet-Teller surface area of the activated carbon obtained from the residue was 387 m(2)/g. After NaOH-HCl demineralization, the reactivity between steam and char was reduced and the surface area of the activated carbon was increased. The initial ash affects the porosity development. A first-order reaction model between steam and char was established. The apparent activation energy was ascertained by Arrhenius equation.