We report the half-metallic properties of the Mn-doped ALP compounds using the full-potential linearized augmented plane wave (FPLAPW) method within the generalized gradient approximation (GGA) embedded in WIEN2k code. Geometry optimization for the Al1-xMnxP compounds was carried out for the different Mn concentrations x=0.0, 0.0625, 0.125 and 025 using supercell. The calculated band structure and density of states show that the half-metallic ferromagnetism is stable for the x=0.0625, 0.125 and 0.25 with a total magnetization of 4 mu(B)/f.u. The total magnetic moment is mainly due to Mn-d states occurring around the Fermi level. The half-metallic band gaps are 1.70, 1.52 and 1.68 eV for x=0.0625, 0.125 and 025, respectively. We also performed GGA with the Hubbard correction (GGA+U) to minimize self-interaction errors. (C) 2015 Elsevier B.V. All rights reserved.