Static dielectric properties of 18 binary mixtures of 4,4′-pentyloxy cyanobiphenyl (5OCB) with 4,4′-bis(alkoxy)azoxybenzenes (nOAB) for n = 5, 6 and 7 have been studied in detail. Seventeen mixtures show induced smectic-A (SmA) phase; a few mixtures exhibit nematic phase as well. Pure 5OCB has a large positive dielectric anisotropy while nOAB members have small but negative anisotropy. However, all the mixtures exhibit positive anisotropy. In the mixtures, except those with x 5OCB ≥ 0.85, the values of ε∥, ε⊥ and increase smoothly with temperature. The values of εiso are found to be higher than the values within the mesophases, with a jump at T NI or T SI. Effective values of the dipole moments in the mixtures are found to be less than the values observed in the pure compounds. This suggests that anti-parallel homo-dimers of 5OCB exist in the mixtures as observed in the pure compound. Moreover, at the onset of SmA phase, values of are found to decrease from those in the nematic phase. This implies that additional anti-ferroelectric type of ordering is developed in the induced SmA phase. In all the mixtures the anisotropy parameter Δε decreases with concentration, becomes minimum at x 5OCB = 0.5, and then increases quite fast. Kirkwood correlation factors have also been calculated to find the nature and extent of the molecular associations.