Transcendental equations have to be solved in order to extract surface exchange and diffusion coefficients from transient techniques. In this work, numerical evaluations of the equation beta(n)tan beta(n) = A, frequently used for a thin plane sheet geometry, have been studied in detail. Based on the Newton-Raphson method and the characteristics of the tangent function, a fast and stable algorithm was suggested to solve this equation for all values of A, which has so far not been the case in the literature. Moreover, a numerical approach to the transcendental equation used in a spherical geometry was also brought up. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.