Because　of　the　unusual　structure　chamber　compared　with　traditional　engines,　gasoline　rotary　engine　always　encounters　partial　burning　and　increased　noxious　emissions　at　the　idle.　Hydrogen-addition　could　enhance　the　characteristics　of　combustion　and　emissions　of　sparked-ignited　engines　at　idle.　A　modified　gasoline　rotary　engine　with　electronic　spark　control　and　fuel　(gasoline　and　hydrogen)　port-injection　system　was　developed　to　study　the　impact　of　hydrogen-addition　on　idle　performance　of　a　gasoline　rotary　engine.　A　hybrid　electronic　control　unit　was　invented　to　manage　the　spark,　fuel　injection,　hydrogen　volume　fraction　of　the　total　intake　and　overall　excess　air　ratio.　In　this　study,　the　engine　was　operating　at　the　idle　speed　of　2400　rpm　and　stoichiometric　conditions.　The　hydrogen　volume　fraction　was　gradually　varied　from　0%　to　6.8%.　Results　showed　that　the　coefficient　of　variation　in　speed　and　fuel　energy　flow　rate　were　both　decreased　after　the　hydrogen　addition.　Flame　development　and　propagation　periods　were　shortened　owning　to　hydrogen-addition.　The　peak　chamber　temperature　was　enhanced　after　the　hydrogen　addition　due　to　the　high　adiabatic　flame　temperature　of　hydrogen.　Cooling　loss　was　dropped　when　hydrogen　was　added　into　gasoline.　HC,　CO　and　CO2　emissions　were　reduced　by　79.4%,　86.0%　and　25.9%　when　hydrogen　volume　fraction　were　raised　from　0%　to　6.8%.　(C)　2017　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.