A thorough investigation of the absorption coefficient dependence on temperature and pressure has been performed for water vapor and a 32-group database has been assembled for H2O mixtures at atmospheric pressure, based on the multi-group full-spectrum correlated k-distribution model. The method is fully scalable, i.e., spectral groups from the database can be combined to obtain coarser group models (N = 1, 2,4,...) for greater numerical efficiency (accompanied by slight loss in accuracy). The databases for CO2 and H2O, together with the random-overlap mixture model have been used to simulate a practical combustion problem. (C) 2003 Elsevier Ltd. All rights reserved.