Abstract In this work, the fluid flow, heat transfer, and combustion processes for a plancha-type biomass cookstove are numerically studied. This approach takes into account the numerical solution of mass, momentum, thermal energy, and chemical species conservation equations by using ANSYS Fluent™. Besides the fluid domain, a solid one representing the metallic comal is also considered for the simulations. In particular, numerical results for the CO2 mass flow rate emissions, unburned volatile combustion efficiency (UVE), and thermal efficiency are compared with experimental Water Boiling Tests (WBT) data. For different firepower values, a good comparison is observed. Differences between numerical and experimental results are in the ranges of 2–9% and 1–2% for the CO2 mass flow rates and combustion efficiencies, respectively. Results indicate that the thermal efficiency is higher for the low firepower cases, which is in agreement with experiments.