The purpose of this research was to perform dry and wet forward combustion experiments for Turkish heavy oil reservoirs (Raman, Adiyaman and Camurlu and Bati Kozluca) under different experimental conditions. In the experiments, a vertical tube was packed with crushed limestone and saturated with crude oil and water. It was observed that peak temperatures were higher when stabilized combustion was achieved and decreased as the combustion front approached the outlet end of the tube. In wet combustion experiments, the rate of combustion reaction and therefore rate of heat generation were reduced with the resultant drop in peak temperatures. In dry and wet combustion experiments, excess carbon-dioxide productions were observed due to the decomposition of carbonate minerals. Atomic H/C ratio of the fuel consumed decreased as the average peak temperature increased. Fuel consumption rate was higher for dry combustion experiments as the degrees API gravity of the crude oils increased, A decrease is also observed in fuel consumption rate after the water-air ratio value is reached to optimum value. For high water-air ratio in wet combustion experiments, a general decrease was observed as the degrees API gravity of the crude oils increased. (C) 2001 Elsevier Science B.V. All rights reserved.