Self-association of alcohols; including ethanol, methanol, cyclopentanol and octanol in separate mixtures with inert solvents have been studied using FT-IR spectroscopy. Except for the band at 3640 cm–1 in the IR spectrum of the alcohols which is due to the monomer species, the presence of other bands in the region of stretching vibrational frequencies of OH (3100-3700 cm–1) are attributed to the higher associated species such as dimmer, trimer and multimers. Association models of such as trimer, continuous linear association model, linear association with cyclic trimer (LACT) and dependent equilibrium constant model (DECM) have been used for treating the IR Spectroscopy results. The calculations indicated that the dominant species in the studied concentration range of alcohols is the trimer. The evaluated association constants in the best-fitted model (timer or LACT) were utilized to obtain the excess properties such as hE, gE and activity coefficients for the mixtures.