The adsorption behavior of gas mixtures composed of hydrogen sulfide and dimethyl sulfide in the pores of N-containing activated carbon (N-CAC) was investigated on the basis of adsorption isotherms of the pure components and binary gas mixtures. Hydrogen sulfide and dimethyl sulfide were mainly adsorbed into smaller micropores and into larger micropores, respectively. The adsorption capacity of N-CAC for hydrogen sulfide was increased by 25-35% as compared with that of raw activated carbon (R-AC). The adsorption capacity of N-CAC for dimethyl sulfide was decreased by 20% as compared with that of R-AC. The experimental adsorption isotherms of binary gas mixtures at 'different molar ratios agreed closely with the theoretical adsorption isotherms on N-CAC. However, the experimental adsorption isotherms of the binary gas mixtures did not agree with the theoretical adsorption isotherms on R-AC and the amounts adsorbed on R-AC were very much smaller than the theoretical ones. These results indicated that adsorption of each component on N-CAC did not interfere with that of the other component, and that hydrogen sulfide and dimethyl sulfide entered micropores of different sizes in N-CAC. It was concluded that N-CAC is a characteristic adsorbent having a greater adsorption capacity for hydrogen sulfide in these binary gas mixtures. It seemed that adsorption of the binary gas mixtures was mainly competitive on R-AC and selective on N-CAC.