In situ combustion of a water-in-oil emulsion layer supported on water is a complex process. In this paper, the combustion process of water-in-oil emulsion layers floating on top of a water body, as in the case of in situ burning of oil spilled at sea that has turned into emulsion, is modeled by using comprehensive mathematical treatment, and the results are compared with data obtained in our lab. The burning process model is divided into three regimes, as follows: 1. The initial regime begins when the emulsion layer floating on the ocean surface receives heat flux from an external source, such as an igniter or a burning oil pool; 2. The intermediate regime begins from the instant of the first appearance of an oil layer on the top of the emulsion layer due to breaking of the emulsion and continues until the oil starts to evaporate; 3. The final regime begins with the combustion of oil vapor, and ends when the fire extinguishes. The laboratory tests were conducted: 1) to establish a critical (i.e., minimum) external heat flux value to cause self-sustaining combustion of the emulsion layer for various emulsion compositions, and 2) to generate burn rate and other emulsion pool fire characteristics, such as time for emulsion separation, burn rate, burn time, and residue Volume left. Measurements were made for emulsions of commercial no. 2 diesel oil, having 20% to 80% water by volume. The model was solved numerically by using finite difference method. Predictions from the model match well with the data.