The dependence of the electronic and magnetic properties on the atomic arrangements of three different phases (i.e. α, β, and γ phases), of the half-Heusler alloy PdMnBi, is investigated based on spin-polarized density functional theory. For each phase, the optimized lattice constant is determined and the possibility of finding a half-metal is explored. Throughout this study, the bonding features of each phase are not supported by the large electronegativity of Pd given in the public domain. Both α and β phases PdMnBi show half-metallic (HM) properties for a range of lattice constants, and their magnetic moments are consistent with the values given by the modified Slater-Pauling rule. Additionally, the effects of the spin–orbit (S-O) interaction are examined by comparing the relative shifts of the valence bands and the indirect semiconducting gap, with respect to the spin-polarized results.