Densities, refractive indices, and speeds of sound at 298.15 K and isobaric vapor-liquid equilibria (VLE) data at 101.3 kPa were reported for the binary mixtures methanol + 2-methyl-1-butanol and ethanol + 2-methyl-1-butanol. Excess molar volumes, refractive index deviations, and changes of speed of sound on mixing were calculated from the measurement results that were fitted with Redlich-Kister polynomials. VLE experimental data were tested for thermodynamic consistency by means of a modified Dechema test and were demonstrated to be consistent. The activity coefficients were correlated with the Margules, van Laar, UNIQUAC, NRTL, and Wilson equations. The ASOG model also was used for prediction.