Abstract Measurements of static dielectric constant at 1 Mc, refractive index (for sodium D-line) and complex dielectric constant at 9.44 GHz (X-band) have been made to determine the relaxation times and dipole moments of N,N′-dimethylaniline (A), N,N′-diethylaniline (B), o-chloroaniline (C), m-chloroaniline (D) and p-chloroaniline (E) in dilute solutions of non-polar solvents. Substances A, B, C and D have been studied in n-heptane, benzene decalin and Nujol. The measurements for A and B have also been extended to cyclohexane, whereas E has only been studied in benzene. The values of relaxation time, calculated by Higasi’s equations in terms of a0, a′, a″ and a∞, and those of α, calculated from Cole-Cole’s equation in terms of the same parameters, showed an evidence for the existence of more than one relaxation mechanism. This has been interpreted in terms of the intramolecular rotations of the amino (or the substituted amino) group occurring simultaneously with the overall molecular orientation.