Anion-exchange membrane fuel cells (AEMFCs) have emerged as an alternative technology to overcome the technical and cost issues of proton-exchange membrane fuel cells (PEMFCs). In this study, we describe a new electrocatalyst for AEMFCs composed of carbon nanotubes (CNTs), KOH-doped polybenzimidazole (PBI) and platinum nanoparticles (Pt), in which the CNTs are wrapped by KOH-doped PBI at a nanometer thickness and Pt is efficiently loaded on the wrapping layer. In the electrocatalyst, it is revealed that the CNTs and the KOH-doped PBI layer function as electron-and hydroxide-conductive paths, respectively, and the large exposed surface of the Pt allows an effective access of the fuel gas. Quantitative formation of the well-defined interfacial structure formed by these components leads to an excellent mass transfer in the catalyst interface and realizes a high fuel-cell performance. Membrane electrode assemblies fabricated with the electrocatalyst show a high power density of 256 mW cm(-2). To the best of our knowledge, this is the highest value for AEMFC systems measured in similar experimental conditions.