Velocities of longitudinal ultrasonic waves have been measured at room temperature for substituted thiazolidines in acetone (w:v %) using pulse-echo technique. Data of the measured ultrasonic velocity and density were used to evaluate many acoustical and volumetric parameters, such as specific acoustic impedance, adiabatic compressibility, partial molal volume, intermolecular free length, apparent molal compressibility, relative association and salvation number. The changes in these parameters have been interpreted in terms of acetone concentration. Results showed that, the acoustical and volumetric parameters yielded valuable information about the behavior of acetone in the investigated solutions of thiazolidines.