Ultrasonic velocity dispersion in methylcyclohexane was studied in the frequency range of 0.5 to 5.0 MHz at 60°, 65°, 70°, 75° and 80°C using a variable path interferometer. Necessary corrections for the diffraction of the ultrasonic beam were applied. The velocity data were used to evaluate the relaxation parameters pertaining to the interconversion of the axial and equatorial isomers. The value of the difference in enthalpy, difference in entropy and the activation energy are 11.2±4.0 kJ mole−1, 28.0±8.0 J mole−1K−1 and 43.7±4.0 kJ mole−1 respectively. These values are in good agreement with values derived by Piercy and Subrahmanyam from their ultrasonic absorption measurements.