The binary interaction parameter, k(ij), of 268 nonpolar mixtures were determined from the database of second cross virial coefficients containing 1728 experimental data points by fitting the second cross virial coefficients with a new correlation for pure compounds [L. Meng, Y.Y. Duan, L. Li, Fluid Phase Equilib. 226 (2004) 109-120] and classical mixing rules. Regularity distributions were found for both n-alkane/n-alkane binaries and fluorocarbon/fluorocarbon binaries. Correlations were developed following Tsonopoulos' ideas [C. Tsonopoulos, Adv. Chem. Ser. 182 (1979) 143-162] with the quantity of binary compounds enlarged using Dymond's latest complication [J.H. Dymond, K.N. Marsh, R.C. Wilhoit, Virial Coefficients of Pure Gases and Mixtures, Subvolume B, Virial Coefficients of Mixtures, Series IV/21B, Landolt-Bornstein, 2002]. Correlations were also developed for inorganic/n-alkane binaries using new k(ij) values. The predictions do not need any thermodynamic property parameters besides the carbon number. Comparisons with the existing correlations show that the present work is more accurate for nonpolar binary mixtures. (c) 2005 Elsevier B.V. All rights reserved.