Corncob, a widespread and inexpensive natural resource in China, was used to prepare activated carbon (AC) by chemical activation with potassium hydroxide (KOH). The adsorption equilibrium and kinetics of H(2), CH(4), and CO(2) on AC were investigated at different temperatures. Adsorption isotherms of H(2), CH(4), and CO(2) were correlated with the Langmuir and Freundich equations, and the heat of adsorption was determined. It was revealed that the Freundich adsorption equation was more apt to describe the adsorption procedure of H(2), CH(4), and CO(2) compared to the Langmuir equation. Two simplified kinetic models including pseudo-first-order and -second-order equations were used to evaluate the adsorption processes. The results indicated that the adsorption of H(2), CH(4), and CO(2) could be described properly by a pseudo-second-order equation. The kinetic parameters of this model were calculated and discussed.