The rate of vibrational energy relaxation (VER) is a valuable probe of microscopic intermolecular interaction. In the present article, the VER rate of the T-1u CO stretch of W(CO)(6) is measured in binary solutions composed of ail alkane (hexane, decane, tetradecane) and cyclohexane or CCl4, with seven mixing volume ratios. The volume ratio dependence indicates that, among the three alkane-cyclohexane solutions, only decane shows ail exceptionally strong contribution to the VER process. It is strongly suggested that decane forms a specific solute-solvent complex with W(CO)(6). The "V-shaped" dependence of the VER rate on the number of carbons in alkane solvents (Banno, M.; Sato, S.; Iwata, K.; Hamaguchi, H. Client. Phys. Lett. 2005, 412, 464.) is explained by the solute-solvent complex model. There are no experimental results that suggest the formation of the specific solute-solvent complex in alkane-CCl4 solutions.