In this study, the direct methanol fuel cell performance of Nafiono/poly(vinyl alcohol) (PVA) blend membranes at 5, 10, and 20 wt% PVA (annealed at 230 degrees C) was investigated at various methanol feed concentrations (2, 4, 8, and 16 M) and compared to the performance of Nation (R) 117 at similar membrane thicknesses and fuel cell conditions. For Nation (R) 117, the maximum power density decreased three-fold when the methanol feed concentration increased from 2 to 16 M. The Nation (R)/PVA (5 wt% PVA) blend membrane reveals a similar trend, however the decrease in power is only 26% compared to 47% when methanol concentration is increased from 2 to 8 M. Furthermore, the maximum power density of the blend membrane (5 wt% PVA) is higher than Nation (R) 117 at 2, 4, and 8 M methanol feed concentrations, while the maximum power density at 16 M is comparable between the two membranes. Specifically, at 8 M methanol, the maximum power density of the blend at 5 wt% PVA is 33% higher than Nation (R)' 117. Blend membranes at higher PVA concentrations are noticeably lower in performance compared to Nalion (R) 117. Overall, fuel cell performance trends match observed transport property (proton conductivity and methanol permeability) trends. (c) 2006 Elsevier B.V. All rights reserved.