It is shown that a mapping of precomputed rate data can be used to implement efficiently detailed surface mechanisms into reactor simulations. The procedure is demonstrated using a surface mechanism for CH4 oxidation on platinum (11 surface species, 19 reactions). It is found that a spline representation based on 7000 data points reproduces the effective CH4 conversion rates with an error of less than 0.5%. To demonstrate the potential of the approach a 3D model of a monolith channel including the irregularly shaped washcoat is implemented in a commercial CFD program. A steady state solution of this model takes 20 s on a 1.5 GHz Pentium computer. This corresponds to a speed up of three orders of magnitude compared to the solution of the same model coupled to a full numerical solution of the surface chemistry. (c) 2008 Elsevier Ltd. All rights reserved.