Microwave-assisted sol-gel method has proven to be a better alternate to conventional chemical approaches. In the present research work, chromium (Cr) doped thin films of iron oxide are prepared by modified sol-gel method, i.e. by using microwaves. Samples are prepared with microwave power of 720 W, whereas doping is varied in the range of 0 to 14 wt%. Maghemite phase (γ-Fe2O3) is observed for undoped sample, whereas hematite (α-Fe2O3) is observed for the samples prepared with 2–4 wt% Cr doping. Magnetite (Fe3O4) phase of iron oxide is observed at relatively higher doping concentrations, i.e. 6–10 wt%. Ferromagnetic behaviour along with high saturation magnetization is observed with the increase in Cr doping concentration. Increased value of squareness is observed at higher Cr concentration, i.e. 6–14 wt%. Higher value of saturation magnetization (Ms) is observed with 10 wt% Cr doping i.e. ~83 emu/g, whereas decrease in Ms is witnessed with further increase in dopant concentration to 12–14 wt%. Impedance measurements show that transport mechanism in Cr doped Fe3O4 is governed by tunnelling across the grain boundaries. Room temperature coupling of magnetic and dielectric behavior is observed under the effect of different frequency values.Graphical Abstract