Department of Physics, Bareilly College, Bareilly, 243005, India

Corresponding Author Email: aksnmr@gmail.com

Present communication reports the experimental values of the dielectric relaxation time () of 4 Methoxyaniline, 4 Ethoxyaniline, 2 Nitroaniline, 2 Chloro, 4 Nitroaniline, 2,6 Dichloroaniline and 2 Methoxy, 3 Nitroanilinein dilute solution of benzene at wavelength 3.13 cm in the microwave region. The measurements have been made at 293, 303 and 3130K, in order to calculate the free energy of activation for dipole orientation process (F). The experimental values ofhave been correlated with the calculated value of obtained using different theories of dielectric relaxation time (  ). It is concluded from this comparative study that the Murty equation is a better representation of the dielectric relaxationphenomenon. Thermo dynamical parameters like molar free energy of activation (F), molar enthalpy of activation (H) and molar entropy of activation (S) have been evaluated by considering the relaxation as the rate process. From the values of F for the various compounds investigated conclusion has been made that energy of activation increases with the size of molecule.