To solve the water flooding problem of micro passive direct methanol fuel cell (DMFC), plasma electrolytic oxidation (PEO) was adopted to prepare a superhydrophilic coating on the surface of an aluminum-based cathode current collector which contacts with air. Results data show that liquid water spreads quickly as a plane on the surface of the porous PEO coating that is composed of Al2SiO3 and Al2O3. As a result, water droplet can be prevented from accumulating along the air-breathing channels of the PEO-treated cathode current collector, and thus the water flooding problem of the micro passive DMFC is effectively solved. The cell fabricated with the novel cathode structure gives excellent stability. (C) 2014 Elsevier Ltd. All rights reserved.