ABSTRACTThe large increase in antibody titers over the past two decades has created significant challenges for downstream processes; however, there have been no quantitative studies of the effect of feed concentration on the dynamic binding capacity in Protein A chromatography. Small scale experiments were performed using pre‐packed ProSep® Ultra Plus columns over a range of feed flow rates and antibody concentrations. The data clearly demonstrate that the dynamic binding capacity decreases with increasing concentration of the monoclonal antibody at short residence times. This reduction in DBC is due to non‐equilibrium mass transfer effects in the porous resin, with the experimental results consistent with predictions of a simple mathematical model based on a linear driving force with solid phase diffusion. These results provide important insights into the behavior of Protein A chromatography and provide a framework for the proper design of Protein A capture steps for high titer products. Biotechnol. Bioeng. 2013; 110:2445–2451. © 2013 Wiley Periodicals, Inc.