Mass transport is of paramount importance to the electrochemical performance of fuel cells. The high performance of fuel cells requires a large diffusion coefficient, i.e. the diffusivity, of the gas transport in electrodes and efficient gas diffusion can lead to large limiting currents and controlled concentration polarization. Recently-designed electrochemical devices allow for the direct evaluation of gas diffusivity in fuel cells. To realize these devices, a gas pump and an oxygen sensor are typically attached to two different spots of the inside wall of an electrolyte tube, which inevitably induces the uncertainty in measurement temperature. To eliminate temperature uncertainty in the diffusivity measurement, an electrochemical device with a multifunctional sensor is designed in this report. Quantitative analysis shows that temperature uncertainty can indeed induce substantial evaluation errors of gas diffusivity, limiting current density and concentration polarization, which in turn verifies the necessity of the multifunctional sensor device for the accurate diffusivity measurement in fuel cells. (C) 2013 Elsevier B.V. All rights reserved.