A model for predicting shunt/leakage currents in a bipolar electrolyzer stack with dual electrolyte inlets and significant amount of gases in the outlet ports and manifold is presented. Model includes electrolyte, manifold and membrane separator as resistance components in the electric circuit analog of the stack. Activation overvoltage associated with electrodes is taken as Tafel-like. Current balance and potential balance equations are applied to the stack and difference calculus is employed to reduce the problem to a set of linear difference equations with constant coefficients. The model is validated with published results and the effect of each resistance component and number of cells on leakage currents in the stack is presented.