Stoichiometric and non stoichiometric magnesium ferrite (MgFe 2+δO4, δ=0.0, 0.1) were synthesized by the sol gel combustion method resulting in nanocrystalline powders with size ranging from 10 to 100 nm. These powders were calcined at various temperatures (300-800 °C). One part of the calcined powder was quenched in liquid nitrogen and the other part furnace cooled. α-Fe2O3 was observed in all calcined samples by XRD and this was also reflected in the magnetization data. Electrical response of MgFe2.1O4+δ spinel phase to 75 ppm ethanol was found to be greater than that for a stoichiometric magnesium ferrite. © 2014 Elsevier B.V.