Following the work of Juris and Wenzel, an alternate combining rule is proposed for cubic equations of state (CEOS). A wide variety of interactions between unlike molecules can be represented effectively by this combining rule.The Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) equations of state (EOS) have been used to assess the usefulness of the alternate combining rule in describing the types of unlike interactions encountered in asymmetric mixtures. In addition, a study was undertaken to evaluate the predictive capability of both equations of state in representing vapor-liquid equilibrium (VLE) of asymmetric binary mixtures, involving methane, ethane, nitrogen, hydrogen, carbon monoxide and carbon dioxide in n-paraffins (C-4-C-44).EOS binary interaction parameters generated by the proposed combination rules are presented for the systems considered. The quality of the EOS representation is dependent on the level of complexity applied in the parameter regressions. Overall, average absolute deviations of 1-3% are realized from the various regression scenarios. In addition, generalized EOS parameter correlations for system-dependent parameters have been developed. These generalized interaction parameters represent the solubilities of the selected systems within 5%. (C) 2003 Elsevier B.V. All rights reserved.