Ammonia　(NH3)　decomposition　to　release　COx-free　hydrogen　(H2)　over　non-noble　catalysts　has　gained　increasing　attention.　In　this　study,　three　nanostructured　CeO2　with　different　morphologies,　viz.　rod　(R),　sphere　(Sph),　and　spindle　(Spi),　were　fabricated　and　served　as　supports　for　Ni/CeO2　catalyst.　The　CeO2　supports　are　different　in　particle　sizes,　specific　surface　area　and　porosity,　resulting　in　the　formation　of　Ni　nanoparticles　with　distinguished　sizes　and　dispersions.　The　surface　properties　of　the　Ni/CeO2　catalysts　are　not　only　distinct　but　also　influential,　affecting　the　adsorption　and　desorption　of　NH3,　N2,　and/or　H2　molecules.　The　Ni/CeO2-R　catalyst　shows　superior　catalytic　activity　compared　to　the　other　two,　owing　to　its　smaller　Ni　crystallite　size　and　larger　BET　surface　area.　The　most　abundant　strong　basic　sites　are　observed　for　Ni/CeO2-Spi　catalyst　based　on　its　exposed　CeO2(110)　planes,　which　facilitates　the　donation　of　electrons　to　the　Ni　particles,　benefiting　the　associative　desorption　of　N　atoms.　Thus,　Ni/CeO2-Spi　shows　higher　catalytic　activity　than　Ni/CeO2-Sph,　despite　their　almost　identical　Ni　crystallite　sizes.　©　2022