A two-dimensional mathematical model for a flow-through porous electrode, in which the electrolyte flow is perpendicular to the current flow, is presented in this paper. In order to study the effects of ohmic resistance, mass transfer and kinetics on the performance of the porous electrode, a set of dimensionless parameters were imported into the model equations. The results reveal that lower ohmic resistance lead to a more uniform current density distribution, which will get a higher utilization of the electrode; an enhancement in convective mass transport will increase the reaction rate, but the increase is in a diminishing manner due to the limit of diffusion rate, so that the effective reaction layer will get thinner until to a limited value; an increase of local mass transfer coefficient will increase the reaction rate and make the effective reaction layer thinner; and the longer the electrode is, the worse the concentration polarization will be. The model could help to guide the rational design of the porous electrode and the operating parameters.