A　series　of　Ni　catalysts　were　prepared　from　Ni-Al　hydrotalcite-like　compounds　(HTlcs)　by　varying　the　Ni/Al　molar　ratio　(1-4)　and　calcination　temperature　(773-1173　K)　of　HTlcs.　The　catalysts　were　reduced　with　H-2　at　1073　K　and　tested　for　CH4　decomposition　at　773-923　K　on　a　thermal　gravimeter.　Various　techniques　including　N-2　physical　adsorption,　XRD,　H-2-TPR,　XPS,　HAADF-STEM,　TEM,　and　Raman　were　applied　to　characterize　the　catalysts　and　the　as-produced　carbon.　The　characterizations　show　that　calcination　of　Ni-Al　HTlcs　leads　to　Ni(Al)O　solid　solution　and　minor　NiO　and/or　NiAl2O4　spinel　may　be　formed　depending　on　the　Ni/Al　ratio　and　calcination　temperature;　upon　reduction　at　1073　K,　most　nickel　species　are　reduced　to　metallic　Ni.　In　CH4　decomposition,　carbon　yield　shows　a　volcano-type　dependence　on　the　Ni　content　with　the　optimum　Ni/Al　ratio　equal　to　3.　On　the　otherhand,　carbon　yield　is　affected　by　the　calcination　temperature　of　the　Ni3Al　HTlcs　to　a　small　extent.　Carbon　yield　is　also　significantly　affected　by　the　reaction　temperature,　which　decreases　remarkably　with　a　rise　of　temperature　to　923　K.　TEM　and　Raman　indicate　that　fish-bone　carbon　nanofibers　are　formed　at　773-823　K,　whereas　multi-walled　carbon　nanotubes　are　formed　at　873-923　K.　(C)　2020　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.