Knowledge of solubility of hydrogen in hydrocarbon systems is important in design and operation of units and equipments in petroleum and coal processing plants for upgrading fuels quality. In this paper a method based on regular solution theory is proposed for prediction of solubility of hydrogen in hydrocarbons, petroleum fractions and coal liquids at different conditions of temperature and pressure. Hydrogen solubility parameter is calculated through solvent type or its molecular weight. Evaluation of results shows that the method can predict solubility data within the same range of accuracy as those calculated from an EOS or other models while this method is simpler and does not require critical properties of solvent which in most cases cannot be estimated accurately. For more than 400 data points and for systems consisting pure hydrocarbons, coal liquid and petroleum fractions the AAD for the proposed model from estimating solubility of hydrogen and Henry's constant for pressures up to 160 bar was about 5%. The proposed method is applicable to fractions with molecular weight ranging from 70 to 650 which is equivalent to carbon number ranging from 6 to 46. The temperature and pressure ranges are 283-623 K and 1-160 bar, respectively. Solubility range is from 0.01 to 26 mol%. (C) 2007 Elsevier Ltd. All rights reserved.