Densities, viscosities, and refractive indices of mixing of methyl ethyl ketone with 1-pentanol, 2-pentanol, and 3-pentanol have been measured as a function of composition range at temperatures (298.15, 308.15, and 318.15) K and ambient pressure. Excess molar volumes V(m)(E), viscosity deviations Delta eta, and refractive index deviations Delta(nD) were calculated and correlated by the Redlich-Kister-type function to derive the coefficients and estimate the standard error. From the experimental data, partial molar volumes, (V) over bar (m,i), and partial molar volumes at infinite dilution, (V) over bar (0)(m,i) were also calculated. The latter values are interesting from a theoretical point of view since at infinite dilution the only interactions present are solute-solvent interactions. The effect of temperature and -OH group position of pentanol isomers on the excess molar volumes, viscosity, and refractive index deviations of its mixtures with methyl ethyl ketone is discussed in terms of the nature and type of intermolecular interactions in binary mixtures.