© 2019 Elsevier B.V.Theoretical calculations of Al0·75Co0·25Sb diluted magnetic semiconductor (DMS) were investigated by using both GGA and TB_mBJ methods. First, the energy-volume optimization curves of AlAs and Al0·75Co0·25Sb compounds were plotted and the ferromagnetic (FM) phases were observed to be more energetically stable. The spin-up states showed metallic properties while the spin-down states had a semiconductor nature. While these properties did not change, some differences were observed in the band gap values. Fermi energies were calculated as 0.298 and 0.462 R y and band gap values were obtained as 0.229 and 0.855 eV by using GGA and TB_mBJ methods, respectively. The values of the total magnetic moments did not change and they were obtained as 2.00 μB/f.u. in both methods. Finally, the elastic properties of Al0·75Co0·25Sb compound were calculated. According to these results, Al0·75Co0·25Sb compound is a brittle half-metal ferromagnetic material and it is suitable for use in spintronic applications.