In　heterogeneous　catalysis　that　involves　metal　oxides,　the　performance　of　catalysts　is　usually　determined　by　the　presence　and　nature　of　oxygen　vacancies.　In　this　article,　we　report　the　synthesis　of　Ni/Ce1−xZrxO2　catalysts　for　ammonia　(NH3)　decomposition　with　their　properties　tuned　by　controlling　the　level　of　Zr　doping.　In　situ　and　ex　situ　spectroscopic　investigations　confirm　the　formation　of　Ce1−xZrxO2　solid　solutions,　and　with　Zr　doping　there　is　an　increase　of　Ce3+　and　oxygen　vacancy　concentration.　At　600　°C　and　30　000　mL　gcat−1h−1,　the　Ni/Ce0.85Zr0.15O2　catalyst　exhibits　an　NH3　conversion　of　~90%　with　superior　stability　in　a　test　period　of　80　h.　Characterizations　of　the　reduced　(in　situ)　and　used　catalysts　confirm　the　integrity　of　the　catalyst.　The　results　of　temperature-programmed　surface　reaction　reveal　that　the　enhanced　catalytic　performance　can　be　ascribed　to　the　associative　desorption　of　N2　at　a　relatively　low　temperature.　This　work　demonstrates　a　general　approach　of　isovalent　ion　doping　to　engineer　metal　oxide　heterogeneous　catalysts　with　properties　tuned　for　a　target　process.　©　2021