A sulfonic group (up to 200 &mgr;mol/mL) membrane was incorporated to epoxy-activated microporous hollow fibers to obtain high-capacity convective ion exchangers. The pure water flux through the membrane decreased exponentially with sulfonic group density and protein binding capacity increased accordingly. At sulfonic group density of 70 &mgr;mol/mL, the membrane lysozyme maximum binding capacity was 84 +/- 9 mg/mL in comparison with its theoretical monolayer maximum binding capacity of 20 mg/mL, thus evidencing tentacle formation. After a cycle of adsorption in a 30 mM sodium phosphate buffer, pH 7. 0, adsorbed lysozyme could be quantitatively recovered following elution with 0.5 M NaCl in the same buffer. Dynamic capacity for lysozyme was 67% of maximum binding, and this value did not change at space velocities ranging from 10 to 40 min-1 as shown by the superimposition of the corresponding breakthrough curves. A cartridge assembled with 21 fibers showed a dynamic-to-static capacity ratio for lysozyme of 0.60 with 1 mg/mL pure lysozyme solution, and 0.42 with a particulate feed composed of 1 mg/mL lysozyme and 0.1 mg/mL yeast.