Abstract: A model is presented for the charge and discharge cyele of a zine-redox battery, based on the available steady-state cell performance model. The cycling model makes use of a quasi-steady-state assumption and includes the effects of crystallization and membrane water transport on the volume of electrolyte during a cycle, as well as variable IR-drop due to conductivity changes. Performance predictions of this model are compared with selected experimental charge/discharge data. Small adjustments to the equilibrium cell potential and cell resistance are made to make the model suitable for design optimization.