Department of Chemistry, Raiganj Sri Sri Ramkrishna Vidya Bhaban, Ukilpara, P.O. Raiganj-733 134, Uttar Dinajpur, West Bengal, India E-mail : uttam mitra@rediffmail.com Manuscript received 22 March 2006, accepted 16 October 2006 A brief report on the physico-chemical properties and structural aspects of some polysubstituted benzenes in benzene at different experimental temperatures under 10 GHz electric field is made to estimate relaxation times \(\tau\)\(j\)'\(s\), dipole moments \(\mu\)\(j\) and thermodynamic energy parameters like enthalpy \(ΔH\)\(\tau\) ,entropy ΔS\(\tau\) and free energy of activation \(ΔF\)\(\tau\) due to dielectric relaxation with formulations derived from orientational susceptibilities \(\chi\)\(ij\)'s, τ's of the polar solutes obtained from the slope of the linear equation of \(\chi\)" \(ij\) and \(\chi\)' \(ij\) are, however, compared with those obtained from the ratio of the linear coefficients of individual variations of \(\chi\)" \(ij\) and \(\chi\)' \(ij\) with weight fractions \(wj\)'\(s\) of the solute. \(tj\)'\(s\) from the later method are used to get thermodynamic energy parameters from the Eyring's rate process equation to shed more light on the physico-chemical properties of the polar liquid molecules concerned. The estimated τ's in terms of linear coefficients \(β\)'\(s\) of \(\chi\)'\(u\)-\(wj\) equations and dimensionless parameters b's involved with measured '\(τj\)'\(s\) are fimilly compared with theoretical dipole moments \(\mu\)\(theo\)'\(S\) obtained from vector addition of available bond angles and bond moments of substituted polar groups. The estimated \(\mu\)\(theo\)'\(S\) gives valuable information regarding structures of the molecules. The slight disagreement between high frequency μj'S and \(\mu\)\(theo\)'\(S\) provides an interesting insight on the inductive, mesomeric and electromeric effects of the substituted polar groups attached to the parent molecules.