A new, simple method of analyzing light elude oil up to C-24, Sampled at high temperatures and pressures, has been developed. The method avoids time-consuming depressurizing procedures. The method utilizes a liquid sampling valve, which endures moderate heating at relatively high pressures. The global composition and number-average molecular weight of the sample is determined with sufficient accuracy. Combined with a PVT software package, the gas/oil ratio and the composition of the gas phase by degassing at 15 degrees C and 1 bar can be predicted.