A new explicit equation is proposed for the determination of immobilized enzyme apparent Michaelis-Menten kinetic parameters in packed-bed reactors. The mathematical analysis is based on recycling systems. The present methodology is easily applicable for a wide range of operating conditions. It is free from the probable limitations of the single-pass apparent immobilized enzyme kinetic parameter estimation technique that requires simultaneous measurement of column substrate inlet and effluent concentrations at a specified time. The experimental system is composed of a substrate reservoir and a circulating flow packed-bed immobilized enzyme reactor. The experimental data is gathered for glucose decomposition reaction in a recirculation system with immobilized glucose oxidase on a weak base ion exchanger resin. The apparent kinetic parameter, K'(m) values were calculated with a new explicit equation, proposed in this work, and they are found to be 0.48 x 10(-3) and 0.60 x 10(-3) mmol cm(-3) for the recirculation rates of 75 and 25 cm(3) min(-1), respectively. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.