Overall　pollutants　emission　from　impinging　premixed　and　diffusion　flames　were　measured　by　investigating　its　dependence　on　burner-plate　separation　distance,　fraction　of　hydrogen　in　the　biogas-hydrogen　mixture,　Reynolds　number　and　equivalence　ratio.　Results　show　that　premixed　flame　is　cleaner　with　both　low　CO　and　NOx　emissions　than　diffusion　flame,　either　under　open　or　impingement　conditions.　Impinging　flame　emits　more　CO　while　less　NOx　than　the　corresponding　open　flame.　For　both　premixed　and　diffusion　flames,　CO　emission　firstly　increases　at　separation　distance　of　H　＜　15　mm　and　then　decreases　at　H　＞　15　mm.　While　NOx　emission　monotonically　increases　with　H.　NOx　emission　also　increases　with　fraction　of　hydrogen,　equivalence　ratio　and　Reynolds　number,　due　to　its　dependence　on　both　temperature　and　volume　of　the　flame.　The　lowest　CO　emission　occurs　at　the　slightly　rich　condition　at　equivalence　ratio　of　1.2.　This　low　CO　emitting　behavior　is　favorable　for　cooking　applications,　where　slightly　fuel　rich　flames　are　adopted.　Copyright　(C)　2015,　Hydrogen　Energy　Publications,　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.