Cu-SSZ-13　catalyst　is　highly　active　for　both　NH3-SCO　and　NH3-SCR　of　NOx.　NH3　conversion　and　N-2　selectivity　were　over　98%　at　225-500　degrees　C　during　NH3-SCO,　while　NOx　conversion　and　N-2　selectivity　remained　above　91　and　98%,　respectively,　at　150-500　degrees　C　during　NH3-SCR.　N2O　formation　showed　bimodal　behavior　with　increasing　temperature　during　both　processes,　with　higher　amounts　of　N2O　produced　in　the　NH3-SCR　process.　Increasing　the　NO　feed　concentration　enhanced　the　conversion　of　NH3　at　low　temperatures　while　promoting　the　formation　of　N2O　at　both　low　and　high　temperatures.　Complete　removal　of　NOx　and　excessive　NH3　can　be　achieved　at　low　temperatures　(e.g.,　250　degrees　C)　by　coupling　NH3-SCR　and　NH3-SCO　over　the　Cu-SSZ-13　catalyst.　O-2　is　necessary　for　both　NH3　oxidation　and　NOx　reduction.　Increasing　the　O-2　content　favored　NH3　oxidation,　leading　to　increasing　NH3　conversion　at　low　temperatures　during　NH3-SCO　and　decreasing　NOx　conversion　at　high　temperatures　during　NH3-SCR.　N2O　selectivity　increased　with　increasing　O-2　during　both　low-　and　high-temperature　NH3-SCO　and　NH3-SCR　processes.　NH3　oxidation　over　Cu-SSZ-13　follows　the　two-step　mechanism:　partial　NH3　is　first　oxidized　to　NO　and　N2O,　and　the　formed　NO　is　reduced　by　the　remaining　NH3　to　N-2　and　N2O.　Nonselective　NH3　oxidation　(NSNO)　and　catalytic　reduction　(NSCR)　contribute　to　N2O　formation　at　both　low　and　high　temperatures.