Microwave processed Ni1-xMgFe2O4 with x=0.0-1.0 are characterized fordc,ac conductivities and dielectric properties as a function of temperature and frequency. Very low dielectric loss tangent is achieved at 5 MHz frequency. Grain and grain boundary contribution towards conductivity is presented on the basis of Nyquist plots and their resistances are evaluated from semi-circular arcs. Equivalent electrical circuits and approximate R-C values are presented for better insight. High dielectric constant of 41 for x= 0.8 sampleinstigated the possibility of good electromagnetic absorption material. A shift in the transport phenomenon is suggested from band like to polaron hopping with rise in temperature.In addition the electromagnetic interference shielding properties are studied in X-band.The results show that the goodelectromagnetic interference shielding efficiency is achieved for x= 0.4-0.6 compositions ranging from 10 to 17 dB (at 8.4 GHz) which is suitable for shielding application. (C) 2017 Elsevier Ltd. All rights reserved.