For system simplicity, it is advantageous to operate the solid polymer fuel cell on dry gases at low overpressures. Under these conditions, water management inside the cell is a critical issue. To determine the effect of operating conditions on performance, a two-dimensional dynamic model is developed. Water balance equations are written for each membrane element taking into account: production, drag and diffusion of water in the membrane, and diffusion of water vapour in the gas diffusion layers. The model can reasonably reproduce the polarisation curves of a cell operated on various oxygen fractions and can qualitatively describe the effect of various operating conditions (dry gases, current density level, co- and counter-flow, anode recirculation).