In the present study, the effect of heterovalent ion doping on the dielectric and ferroelectric behaviour of AgNbO3/AN system was investigated. 0.04 mol of manganese (Mn4+) and tungsten (W6+) ions of smaller ionic radii were substituted in place of niobium (Nb5+) ions in the AN system for generating hole and electron rich compounds, respectively. Better dielectric properties with improved saturation polarisations were observed in the heterovalent ions modified AN ceramics. The relaxation behaviour of the modified AN ceramics was investigated by impedance spectroscopy study and intrinsic grain conduction was found to be dominating in the chosen frequency and temperature ranges. The reduced resistivity of the modified AN ceramics was discussed in terms of calculated activation energy. The significant reduction of the activation energy was proposed as the possible cause of early arrival of relaxation peak in the electron doped AN system. (C) 2016 Elsevier B.V. All rights reserved.