A silica-based medium with optimized pore size, pore volume, and coupling density was prepared for protein A affinity chromatography, to be used for industrial purification of IgG. Performance and durability of the silica-based medium were studied during repeated use and compared with other protein A media available on the market. The silica-based medium provided high dynamic binding capacities for human polyclonal IgG in the superficial liquid velocity range from 150 to 720?cm?h1 because of a high mass transfer coefficient and high mechanical strength. The dynamic binding capacity and IgG recovery were high and varied only slightly during 50150 cycles of repeated use. The release of protein A ligand was low.