Selective recovering and adding back of the desirable odor components from the volatiles evolved from roasted and ground coffee beans in manufacturing of soluble coffee contribute to improve the flavor quality of the product. Surface-oxidized carbons were prepared and characterized to remove methyl mercaptan selectively from coffee volatiles. MSC 5A was ground and oxidized using O₂ at 623 K, and H₂O₂ and HNO₃ solutions. The pore volume and the specific surface area of the prepared carbons increased with the increase of the surface oxides. The oxidation by 13.2 N HNO₃ was most effective for increasing the surface oxides, and the amount of methyl mercaptan adsorbed was around twice that of nontreated carbon. An interesting result was obtained in that the amount of methyl mercaptan adsorbed was further enhanced by a factor of more than five by co-adsorption of acetaldehyde on the oxidized carbon. It was demonstrated that the adsorption selectivity for methyl mercaptan was significantly improved in the quaternary system as a model of coffee volatiles. From characterization of the carbons after desorption at 373 K, it was found that the amounts of methyl mercaptan adsorbed reversibly and irreversibly were increased greatly by co-adsorption of acetaldehyde. It was elucidated that the enhancement of methyl mercaptan adsorption by acetaldehyde was caused by promotion of micropore filling with both adsorbates.