Ammonia　is　a　carbon-free　hydrogen　carrier,　and　development　of　non-noble　metal　catalyst　to　decompose　ammonia　into　hydrogen　is　desirable　for　practical　applications.　However,　the　metal　catalyst　is　challenged　by　the　sintering　of　metal　particles　under　high-temperature　reaction　conditions.　In　this　study,　a　series　of　Li-,　Al-,　and　Co-containing　hydrotalcite-like　compounds　(HTlc)　were　synthesized　by　co-precipitation　and　used　as　precursors　to　prepare　well-dispersed　and　thermally　stable　Co　nanoparticle　catalysts　for　ammonia　decomposition.　The　obtained　precursors　and　catalysts　were　characterized　by　means　of　X-ray　powder　diffraction　(XRD),　temperature-programmed　reduction　(H2-TPR),　X-ray　photoelectron　spectroscopy　(XPS),　high-angle　annular　dark-field　scanning　transmission　electron　microscopy　(HAADF-STEM),　and　so　on.　All　of　the　precursors　formed　hydrotalcite-like　phase,　which　consisted　of　Li–Al–(Co)　HTlc　and/or　Co–Al　HTlc　dependent　on　the　Co　content.　Upon　calcination　at　500　°C,　HTlc　decomposed　into　an　Al-substituted　Co3O4　spinel　oxide,　as　confirmed　by　two　distinctly　separated　reduction　steps　in　H2-TPR.　Following　reduction　at　700　°C,　well-dispersed　Co　metal　nanoparticles　with　an　average　particle　size　of　∼9.2–12.4　nm　were　obtained.　It　was　suggested　that　the　incorporation　of　Al3+　into　Co3O4　led　to　a　strong　interaction　between　cobalt　and　aluminum,　which　suppressed　the　crystal　growth　of　Co3O4　and　the　sintering　of　Co　metal　during　the　thermal　treatments,　resulting　in　good　Co　dispersion.　The　optimal　LiAlCo(1.5)　catalyst　showed　superior　activity　than　that　prepared　by　impregnation　method,　giving　almost　complete　conversion　of　ammonia　at　575　°C　under　a　space　velocity　of　5,000　mL　gcat–1　h–1.　More　importantly,　this　catalyst　maintained　stable　activity　at　625　°C　for　100　h,　exhibiting　high　stability　and　sintering　resistance.　The　good　catalytic　performance　was　attributed　to　the　high　Co　metal　dispersion　and　strong　metal–support　interaction　benefiting　from　the　uniform　distribution　of　cobalt　in　the　HTlc　precursor.　These　results　demonstrate　the　applicability　of　HTlc　to　the　preparation　of　metal　catalysts　with　improved　dispersion　and　thermal　stability.　©　2024　Elsevier　B.V.