In order to investigate the solvation behavior of polycyclic aromatic compounds in cyclohexane and heptane, molar enthalpies of solution, Delta H-soln(m), densities, and sound velocities have been measured for dilute mixtures. And to make the difference in solvation thermodynamic properties between cata-condensed and polyphenyl aromatic compounds clear, the measurements of these properties were carried out for polyphenyl compounds with some aprotic solvents. Molar enthalpies of solvation, Delta H-solv(m), apparent partial molar volumes at infinite dilution, V-m,1(infinity), and apparent partial molar isentropic compressions at infinite dilution, K-s,m,1(infinity), were calculated from the measured thermodynamic quantities. The aromatic compounds investigated were benzene, naphthalene, phenanthrene, biphenyl, and o-, m-, and p-terphenyl. Solvents studied were cyclohexane, heptane, benzene, 1,4-dioxane, and chloroform. The values of Delta H-soln(m) for the polyphenyl compounds were endothermic for all the solvents. The values of V-m,1(infinity), of the polycyclic aromatic compounds in cyclohexane were relatively larger than those in benzene, 1,4-dioxane and chloroform measured in the previous work [M. Ohba, T. Takigawa, H. Ogawa, S. Murakami, Fluid Phase Equilib. 136 (1997) 289-297]. It was found that the values of Delta H-solv(m), V-m,1(infinity), and V-s,m,1(infinity) depend linearly on the number of carbon atoms in the solute molecule, except for those of o- and p-terphenyl. This supports the group contribution principle. Delta H-solv(m) per carbon atom for cata-condensed matter shows an absolute value that is almost the same as that shown by Delta H-solv(m) per carbon atom for polyphenyl one. The value of V-m,1(infinity) per carbon atom is slightly larger for polyphenyl matter than for cata-condensed one. Solvation behavior of the polycyclic aromatic compound molecule in each of the solvent molecules was characterized by plots of the partial isentropic compressibility, K-s,1(infinity), against the cohesive energy density at infinite dilution, epsilon(infinity). The strength of solvation of the polycyclic aromatic compound in a non-polar solvent is not larger than that in a polar one. (C) 2009 Elsevier Ltd. All rights reserved.