The effect of burning on the organic matter of three forest soils, which had been affected by wildfires within one month prior to sampling, was studied using a differential scanning calorimeter (DSC). The soils were cambisols under Pinus spp. located in Galicia (NW Spain). Thermograms of the soils were carried out between 50 and 600 degrees C. The combustion enthalpies of the soils were determined from the thermograms. By comparing the combustion enthalpy data of the burnt soils and that of the corresponding unburnt soils, the loss of organic matter due to the burning was calculated. The ignition temperature for each soil was also estimated from the thermograms.