In this study, a simple and effective technique for characterizing Michaelis-Menten apparent kinetic parameters in packed-bed immobilized enzyme reactors is presented. The apparent kinetic parameters of immobilized glucose oxidase on weak base ion exchanger resin (Duolite A 568) were determined for different substrate flow rates in a recirculation system and compared with those for soluble glucose oxidase. It was observed that, for the experimental conditions, the immobilized enzyme K-m' values in a packed-bed reactor were less than the soluble enzyme K-m value and were flow dependent. The value of K-m' decreased with increasing flow rate.