Dielectric relaxation of binary (jk) polar mixtures of benzonitrile and tetramethyl urea (TMU) with N,methylformamide (NMF) dissolved in benzene (i) for different weight fractions wjk’s of polar solutes and mole function xj’s of NMF at 25, 30, 35 and 40 °C have been studied in terms of relaxation time τjk and dipole moment µjk from conductivity measurement of solution under 9.885 GHz electric field using Debye Model. Solute-solvent and solute-solute association have been predicted from plot of τjk and µjk against xj’s of NMF up to xj=0.5 and beyond xj=0.5 to xj= 1.0, respectively. Estimated τ and µ from both the proposed methods agree with the reported values. Theoretically µ’s have been calculated from bond angles and bond moments of polar groups due to existence of inductive, mesmeric and electromeric effect arising out of microscopic inhomogeneity in them. Molecular dynamics of polar mixtures have been ascertained from Eyring rate equation to establish Debye relaxation mechanism for all systems