Since the particulate mass emission standard has been proposed by EPA for diesel engines. Particulate control technology and particulate measurement have become increasingly important. The main constituents of particulates are carbon and hydrocarbons, their relative content in the particulates varies with different engine configurations as well as sampling systems. The percentage of hydrocarbon in particulate is considered to be important due to the suspected health hazard of polyaromatic hydrocarbons; also due to the mass contribution to the total particulate weight. At present, only total particulates legislation has been considered, therefore, knowing the contribution of hydrocarbon to total particulate is important. In this work, a series of controlled standard experiments was conducted to study the accuracy of solvent extraction and vacuum sublimation processes for the determination of percentage extractable of particulates. Comparison of both techniques was also performed on real particulate samples collected from various engine operating conditions. The results indicate that vacuum sublimation is a reliable technique.