Performances of direct ascorbic acid fuel cells using anodes of nano carbons (SWCNT, graphene, C-60) and their composites with conducting polymers were studied. The output power using polyaniline@SWCNT composite was 8.7 mW cm(-2) for Nafion separator and Pt cathode. Cells using PEDOT*PSS@SWCNT composite and filter paper for separator exhibited power >2 mW cm(-2). The facts are explained by the idea that PEDOT*PSS plays the role of cation exchange membrane.