The invention relates to a method allowing to determine at least one petroleum characteristic of a geologic sediment sample, wherein the sample is heated in an oxidizing atmosphere, its temperature being successively raised to a first, then to a second value, said first value below 200° C. being reached very quickly, then maintained substantially constant for a certain time, said second value ranging between 600° C. and 850° C. being reached with a temperature gradient ranging between 1 and 30° C./min, from said first value. According to the invention, the amount of SO2 contained by the effluent resulting from said oxidizing heating is measured continuously, every moment of the heating period of said sample.