The weighted-sum-of-gray-gases (WSGG) model is widely used in engineering computations of radiative heat transfer in participating media due to its relatively simple implementation and reasonable accuracy. However, a major difficulty arises with its application to general gas mixtures where the mole ratios of the participating components are not constant. The present study presents a WSGG methodology to allow efficient, accurate computation of radiative heat transfer in mixtures of H2O, CO2, and soot with arbitrary concentrations. The method is based on first establishing independent correlations for each species, which are then combined to form the WSGG correlations for the mixture. A few test cases are presented to assess the accuracy of the two methods by comparisons with benchmark solutions obtained with the line-by-line integration (LBL) of the spectrum. (C) 2014 Elsevier Ltd. All rights reserved.