Combustion and synthesis of hydrocarbons may occur directly (CH → C + H and CO → C + O) via a formyl intermediate (CH + O → CHO followed by CHO → CO + H and CO + H → CHO followed by CHO → CH + O) . The activation and reaction energies of these reactions on the Ni(111), Ni(110) and Ni(100) surfaces were investigated using density functional theory (DFT). Calculations show that the barriers are sensitive to the surface structure. The barrier for CH dissociation (catalytic hydrocarbon combustion) is lower than that of for its oxidation reaction (CH + O → CHO) on the Ni(110) and Ni(100) surfaces. In contrast, the barrier for oxidation is lower than that for dissociation on the Ni(111) surface. This means CH will preferably dissociate on the Ni(110) and Ni(100) surfaces, but not on the Ni(111) surface. The barrier for dissociation increases in the order Ni(110) < Ni(100) < Ni(111). The barrier of CHO dissociation to CO and H is almost the same on the Ni(111) and Ni(110) surfaces and it is lower compared to the Ni(100) surface. The energy barrier for carbon monoxide dissociation (catalytic hydrocarbon synthesis) is higher than that of for its hydrogenation reaction on all three surfaces. This means that the hydrogenation to CHO favored over the nickel surfaces studied here. The barrier for both reactions increases in the order Ni(110) < Ni(100) < Ni(111). Formyl dissociation to CH + O barrier is the lowest on the Ni(110) surface and follows the order Ni(100) > Ni(111) > Ni(110). Our DFT results show that the Ni(110) surface has a larger catalytic activity compared to the other surfaces, and that Ni is a better catalyst for hydrocarbon combustion than synthesis.