Densities, ρ, and speeds of sound, u, of 2-pentanone + aniline, + N-methylaniline, or + pyridine systems have been measured at (293.15, 298.15 and 303.15) K and atmospheric pressure using a vibrating tube densimeter and sound analyzer Anton Paar model DSA-5000. The ρ and u values were used to calculate excess molar volumes, V m E, and the excess functions at 298.15 K for the speed of sound, u E, the thermal expansion coefficient, α P E, and for the isentropic compressibility, κ S E at 298.15 K. V m E and κ S Eare both negative magnitudes and increase in the same sequence: aniline < N-methylaniline < pyridine, while u E is positive and increases in the opposite way. The similar trends are observed for mixtures including the same aromatic amines and propanone, 2-butanone or 2-heptanone. The data have been interpreted assuming strong ketone–amine interactions, which become weaker when the chain length of the 2-alkanone is increased in solutions with a given aromatic amine. Ketone–amine interactions are more easily created in mixtures with aniline. Interactions between unlike molecules are stronger than in 2-alkanone + dipropylamine, or + dibutylamine, or + triethylamine systems. These findings are confirmed by the results obtained from internal pressures and molecular interaction parameters for the investigated mixtures.