Composition-uniform　Ni–Cu/Al2O3　alloy　catalysts　have　been　prepared　from　Ni–Cu–Al　hydrotalcite-like　compounds　(HTlcs)　and　tested　for　methane　decomposition　at　650°C.　The　catalysts　were　characterized　by　XRD,　XPS,　H2　chemisorption,　H2-TPR,　STEM-EDX,　SEM,　TEM,　and　Raman.　The　characterizations　reveal　that　calcination　of　Ni–Cu–Al　HTlcs　leads　to　Ni(Cu,Al)O　oxide　solid　solution,　both　nickel　and　copper　ions　being　homogeneously　distributed　in　HTlcs　as　well　as　in　Ni(Cu,Al)O,　and　upon　reduction　the　well-mixed　Cu2+/Ni2+　species　are　step-wise　reduced　to　form　composition-uniform　Ni–Cu　alloy　with　an　average　size　of　9.5–10.4　nm.　Alloying　Ni　with　an　appropriate　amount　of　Cu　remarkably　enhances　the　catalytic　life　and　carbon　yield.　The　highest　carbon　yield　of　132.9　g-C/g-cat　is　obtained　at　atomic　ratio　of　Ni:Cu　=　7:3,　which　is　about　78　times　that　of　the　Ni/Al2O3　counterpart.　Moreover,　carbon　morphology　is　changed　from　thin　CNTs　to　thick　fishbone-CNFs　and　platelet-CNFs　depending　on　the　copper　content.　Under　the　reaction　atmosphere,　Ni–Cu　alloy　is　sintered　to　large　particles　by　contact　with　methane.　It　is　suggested　that　Ni–Cu　alloying　favors　the　formation　of　large　alloy　particles,　which　inhibits　methane　dissociation　and　enhances　carbon　bulk　diffusion,　thus　facilitating　the　CNFs　growth　and　leading　to　a　significant　increase　of　carbon　yield.　©　2022