Laboratory protocols based on water heating procedures represent the most widespread tool for the evaluation of Improved Cooking Stoves (ICSs) thermal performance. Nevertheless, the performance of the cooking system can vary substantially when the boundary conditions – ambient conditions, burn sequence – differ from those experienced in a specific lab. Consequently, we developed and experimentally validated a Cooking Stoves Thermal Performance Simulator (Cook-STePS), based on a 1-D heat and mass transfer model and implemented in an Excel^® and VBA environment, in order to provide additional information about how the performance of a cooking system would change, in selected conditions, as compared to the baseline laboratory performance. The study shows how the tool can be effectively applied to a generic cooking system through a two-steps procedure, based on (i) a preliminary set of experimental tests in controlled conditions and (ii) the simulation of performance in the desired conditions.