An Optimized Emission-based Reciprocity Monte Carlo Method (OERM) has been developed and validated by comparison, in benchmark cases, with analytical reference results. In this method, the frequency distribution function, generally equal to the emission distribution function at the emitting cell temperature, has been replaced by a distribution function associated with the maximum temperature within the domain. The real emission distribution function of a cell at any temperature is then obtained by applying a corrective factor to each shot. (C) 2012 Elsevier Ltd. All rights reserved.