In this study we focus our attention on a strategy to deal with packed-bed catalytic reactors in order to present an alternative methodology for the derivation of a new explicit equation for the determination of apparent kinetics coefficients for first order reactions. The Ozdural-Alkan methodology, originally used in membrane separations, was followed during the analytical solution of the governing PDE of the system whose solution have resulted the explicit equation sought. The apparent kinetics coefficients obtained through the above-mentioned explicit equation were compared and verified with the numerical solution results of the same system where two different numerical techniques were employed independently. It was concluded that the proposed equation successfully predicts the apparent first order kinetics coefficient in recycling packed-bed catalytic reactors with the use of a single reservoir concentration measurement and the corresponding time data. (c) 2006 Elsevier B.V. All rights reserved.