In naturally aspirated wood-burning stoves, the air-flow is driven by buoyancy forces which overcome the flow resistances inside the stove. This air flow, in turn, determines the wood-burning rate as well as the overall thermal and combustion efficiencies. The flow and associated heat/mass transfer and combustion phenomena are 3-dimensional and time dependent. In this paper, a simplified 4-zone well-stirred thermochemical model is developed by capturing steady-state effects of chemical reaction kinetics of char and volatile burning. The model predicts performance parameters such as thermal efficiency, composition of combustion products, and excess-air factors for an experimental stove. Effects of stove geometry, wood fuel characteristics, cooking vessel dimensions, and other ambient conditions are investigated.