The change in free energy of activation (), enthalpy of activation (), and entropy of activation () of poly(ethylene glycol) with average molecular mass 400 Dalton (PEG 400) in dilute solutions of benzene have estimated based on the theory of Eyring rate process. These thermodynamic parameters have been determined using most probable dielectric relaxation times (tau) at different temperatures using Higasi method. Based on the results, the behavior of the stated polymer in non-polar solvent is discussed. The obtained results are compared with those determined using Whiffen and Thompson model.