In this paper, MgAl2O4 nanoparticles were synthesized by the Sol-gel auto combustion method and were doped with different concentrations of Ni2+ (x= 0, 0.1, 0.05, and 0.03). By this method, a novel photocatalyst which had better decolorization percentages of Congo redcompared to MgAl2O4 was produced. The MgAl2O4 sample...