A series of LiNi0.05-x Mg x Mn1.95O4 (0.01≤x≤0.04) compounds were synthesized using microwave irradiation as sintering technique. The structures and electrochemical performances of the as-prepared powders were characterized by XRD, SEM, EDS, TEM, electrochemical galvanostatic cycling tests, EIS and XRF. The XRD and Rietveld refinement results indicate that all samples exhibit a single spinel structure and dual-doping causes the shrinkage of lattice space. The discharge capacities and cycling performances of LiNi0.03Mg0.02Mn1.95O4 are the best with a low capacity fading over the investigated 30 cycles at elevated temperature (55°C). These results demonstrate that the microwave sintering method and metallic ions co-doping are effective ways to suppress the Mn dissolution from active electrodes at high temperature and high rate for lithium-ion batteries.