© 2019 Elsevier B.V. Temperature dependent magnetization of Ni 0.5 Co 1.5 MnSb quaternary Heusler alloy is investigated both theoretically (m-T) and experimentally (M-T). According to the XRD data, the crystal structure of Ni 0.5 Co 1.5 MnSb is compatible with the cubic crystal structure with space group symmetry Fm-3m and the lattice parameter of a = 5.968 Å. Experimental M-T curve is obtained at H = 1 T. The Curie temperature is obtained at about T C EXP = 538.3 K. We also use effective field theory (EFT) developed by Kaneyoshi to model and investigate the m-T properties of Ni 0.5 Co 1.5 MnSb. We find that the theoretical m-T and experimental M-T results overlap at low temperatures (T < 100 K). Additionally, the Curie temperature of Ni 0.5 Co 1.5 MnSb is obtained at T C EFT = 548.1 K and H = 0 T. The discrepancy between the theoretical and experimental value of T C is found to be 9.8 K only. One remarkable outcome of this study is that the central antimony (Sb3) atom has an important role when comparing the theoretical m-T and experimental M-T results of the Ni 0.5 Co 1.5 MnSb at high temperatures (T > 100 K). In particular, the theoretical m Sb3 -T curve of the central Sb3 atom is much closer to the experimental M-T curve of Ni 0.5 Co 1.5 MnSb than that of the other components (m Mn1 , m Mn2 , m Mn3 , m Sb1 , m Sb2 , m Ni and m Co ). Therefore, we strongly propose that one needs to pay close attention to the magnetization of the central atom especially in the lattice of Heusler alloys in both their predictive and experimental studies.