Density functional theory has been employed to investigate the ligand effect in the reaction of ligated NiBr + with propane. Both initial C–H and C–C bond activation mechanisms for losses of HBr, H 2 , and CH 4 are analyzed in terms of the topology of the potential energy surface. Losses of HBr and H 2 involve three C–H activation mechanisms, that is, α , β- H, α , γ -H, and β , α -H abstractions, where the last β , α -H abstraction is the most favorable mechanism. Loss of CH 4 involves initial C–C activation, but it is prevented by the high-energy barrier. When propane reacts with the open-shell ligated NiBr + , the ligand of Br in the initial C–H activation could direct abstract a H atom from propane substrate via a four-center transition state, without forming multi- σ -type bonding of Ni + , whereas the metal center in the initial C–C activation needs to experience an unfavorable three σ -type bonding (with Br, CH 3 , and CH 2 CH 3 ), which explains why HBr and H 2 are formed in the reaction of BrNi + /C 3 H 8 and CH 4 not.