In this study, the quaternary basicity (CaO+MgO/Al2O3+SiO2) with modified MgO and CaO content in the selective reduction of limonitic nickel ore was investigated clearly. Limonitic nickel ore used in the process contains 1.38% Ni and 38.2% Fe. The anthracite coal and 10 wt% of Na2SO4 were used as reductants and additives, respectively. The reduction process conducted at 1150°C for an hour continued with the magnetic separation process to separate concentrate/ferronickel and tailing/impurities. The higher basicity with modified MgO resulted in lower nickel grade due to the formation of more magnesium silicate/forsterite, which could inhibit metal oxide reduction. The 0.3 of basicities with modified CaO addition showed the optimum condition due to its ability to break the silicate structure. © 2023 Author(s).