The prediction of the composition of petroleum fractions and pure hydrocarbon mixtures is a sensitive operation. Up till now, the already developed correlations in the literature are based on experimental data of crude oils. In this work, a new method is proposed for correlations elaboration based on the use of pure hydrocarbons specific data. This technique enables the characterization of the composition (wt%), in paraffins, naphthenes and aromatics, of pure hydrocarbon mixtures and petroleum fractions issued from different crude oils, according to their physical properties that are easily accessible such as normal boiling point (T-b), density (d), refractive index (n) and carbon to hydrogen weight ratio (CH). (C) 2004 Elsevier Ltd. All rights reserved.