A multi-layer zone fire model for a single compartment was developed to predict the vertical distributions of the temperature and the gas concentrations. The basic concept of this model is to divide the fire room volume into an arbitrary number of horizontal layers, in which the temperature and other physical properties are assumed to be uniform. Considering the mass and the enthalpy flow rates through the layer interfaces and the opening and the heat transfer rates for each layer, the zone equations for the temperature and the species mass fractions are derived. The results of the sample calculations are compared with the experiments conducted by Steckler et al. From the comparison, it is considered that the model can be a practical tool to predict the behavior of fire in a room, although continuing effort may be necessary to improve the prediction.