The infrared absorption spectra of aqueous methanol, ethanol, 1- and 2-propanol, t-butanol, and n-butoxyethanol in the region of asymmetric and symmetric C-H stretching modes (3200-2800 cm(-1)) have been measured at 25 degrees C as a function of alcohol concentration in the whole cosolvent mole fraction region. Measurements of adiabatic compressibility were also performed on the same water-alcohol solutions at 25 degrees C. The two sets of experimental data are compared and discussed in terms of a possible mechanism of molecular aggregation in the various regions of alcohol concentration.