A pressurized differential scanning calorimeter (PDSC) has been used to obtain information on the combustion characteristics of crude oils and their mixtures in two chemically different matrix materials, sand and limestone. Crude oil and sand-limestone mixtures were prepared to give a composition of 10 wt % crude oil in matrix. The PDSC curve clearly demonstrates two distinct transitional stages, namely combustion of liquid hydrocarbons and combustion of coke. The kinetic part of this research is concerned with only one peak, namely the coke combustion. Kinetic data were analyzed by two different kinetic models and the results are discussed.