Several recent studies have demonstrated the importance of electrostatic interactions on the transport of charged proteins through porous membranes. The objective of this study is to compare predictions of available hydrodynamic and partitioning models with experimental data for the sieving coefficient of ovotransferrin through both positively and negatively charged membranes over a range of solution conditions. Model calculations were performed with all parameters evaluated from independent experimental measurements. The membrane pore-size distribution was determined from dextran sieving data, and the membrane surface charge was evaluated from streaming potential measurements. The model properly predicts the complex: effects of solution pH and ionic strength on protein transmission in the presence of both attractive and repulsive electrical interactions. Model simulations were performed to highlight the key contributions to protein transport.