Adding　the　product　of　water　electrolysis　(i.e.　2:1　volume　of　H2　and　O2)　is　an　effective　strategy　to　enhance　the　combustion　intensity　of　NH3/air　mixtures.　In　this　work,　the　laminar　burning　velocity　(LBV)　of　the　obtained　NH3/H2/O2/air　mixtures　was　measured　at　303　K,　0.1　MPa　and　compared　with　the　values　predicted　by　seven　mechanisms.　To　improve　the　prediction　performance,　a　new　mechanism　is　developed　based　on　the　existing　mechanism　and　adopted　for　numerical　simulation.　The　results　of　this　study　show　that　the　LBV　of　NH3　is　significantly　increased　by　additional　H2　and　O2.　By　comparison,　it　is　found　that　H2　shows　a　more　significant　promoting　effect　on　LBV　when　the　volume　ratio　of　additional　H2　and　O2　is　2.　The　concentration　of　key　radicals　and　the　flame　temperature　increase　remarkably　due　to　the　addition　of　H2　and　O2,　which　promote　the　flame　propagation.　Furthermore,　the　experimental　results　also　indicated　that　the　additional　H2　and　O2　make　the　burned　gas　Markstein　length　decrease　on　the　lean　side　and　increase　on　the　rich　side.　(c)　2023　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.