Ammonia　decomposition　is　a　promising　approach　for　on-site　hydrogen　generation　for　fuel　cells,　and　the　development　of　a　cost-effective　and　efficient　catalyst　is　highly　desired.　In　this　study,　a　series　of　NixMg75–xAl25　hydrotalcite-like　compounds　(HTlc)　with　different　Ni　contents　were　synthesized　by　co-precipitation,　followed　by　calcination　and　reduction　treatments.　Influences　of　Ni　content　and　ammonia　reduction　on　the　catalytic　performance　for　ammonia　decomposition　were　investigated.　The　characterization　results　of　the　as-prepared　samples　showed　that　HTlc　was　decomposed　into　Mg(Ni,　Al)O　solid　solution　by　calcination,　which　displayed　a　strong　interaction　between　Ni　species　and　support,　while　upon　reduction　with　ammonia　at　750　℃,　well-dispersed　Ni　metal　nanoparticles　with　an　average　crystallite　size　range　of　5.9–7.7　nm　were　formed.　No　nitrogen　oxides　(NOx)　were　produced　during　the　NH3　reduction　process　as　indicated　by　mass　spectrometry　analysis,　and　the　catalyst　reduced　with　ammonia　showed　comparable　activity　with　that　reduced　with　hydrogen,　suggesting　that　ammonia　can　be　used　as　a　reductant　gas.　The　catalyst　activity　increased　with　the　increase　of　Ni　content　and　reduction　temperature.　Among　the　catalysts,　the　Ni20Mg55Al25　catalyst　reduced　with　ammonia　at　750　℃　showed　the　best　activity,　which　afforded　98%　ammonia　conversion　at　600　℃　at　a　space　velocity　of　30000　mL·gcat–1·h–1,　and　no　evident　deactivation　was　observed　during　a　100　h　test,　demonstrating　good　activity,　stability,　and　sintering　resistance.　©　2025　Science　Press.　All　rights　reserved.