In this paper, a new vapor feed fuel delivery system for a passive direct methanol fuel cell (DMFC) is developed and tested. Anode hydrophilic layers, electrical heating power and carbon dioxide release are examined to find their effects on the power density, efficiency and average temperatures of the cell. The hydrophilic layers act as a buffer layer between the vapor chamber and the anode gas diffusion layer (GDL). This layer allows water and methanol to mix, as well as distribute uniformly across the anode surface. Measurement of several parameters such as current, voltage, power, internal resistance, vapor chamber pressure, relative humidity and carbon dioxide concentration are taken. A maximum power density of 33 MW cm(-2) is achieved as well as 120 h of continuous operation at a constant current of 50 mA cm(-2) using the vapor feed system. The fuel utilization efficiency during the 120 h test is 34.8% and the energy efficiency is 8.2%. (C) 2009 Elsevier Ltd. All rights reserved.