Co0.50Mn0.50Ce xFe2− xO4 (with x = 0.000, 0.025, 0.050 and 0.100) nanoparticles were synthesised through sol–gel method. The crystallite size and lattice constant are increased from 30 to 50 nm and 8.375 to 8.384 Å, respectively, with increasing Ce content. It was found that Fe3+ cations migrate towards octahedral sites with Ce doping. The optical band gap was decreased from 1.79 to 1.50 eV whereas saturation magnetisation was decreased from 57 to 49 emu/g with increase in Ce substitution. Maximum dielectric constant and minimum dielectric loss, maximum AC conductivity along with moderate magnetic properties were observed for x = 0.050. So, x = 0.050 may be a potential candidate for electromagnetic interference shielding applications.