This　paper　aimed　to　study　the　effect　of　spark　timing　on　performance　of　a　hydrogen-gasoline　dual-fuel　rotary　engine.　For　this　aim,　a　modified　rotary　engine　equipped　with　a　dual-fuel　port　injection　system　was　developed.　An　electronic　management　module　(ECM)　was　specially　made　to　command　the　fuel　injection,　excess　air　ratio　and　hydrogen　volumetric　fraction.　In　this　study,　the　engine　was　operated　at　4500　rpm　with　a　manifold　absolute　pressure　(MAP)　of　35　kPa.　Hydrogen　volumetric　percentage　of　total　intake　was　kept　at　0%,　3%　and　6%,　severally.　When　the　hydrogen　volumetric　percentage　was　changed,　the　gasoline　fraction　was　also　adjusted　to　keep　the　mixture　at　the　stoichiometric.　For　a　specified　hydrogen　volumetric　fraction,　the　ignition　timing　was　varied　from　24　to　42　degrees　CA　BTDC　(before　top　dead　center)　with　a　fixed　interval　of　2　CA.　Experimental　results　showed　that　for　a　specific　hydrogen　volumetric　percentage,　the　peak　combustion　pressure　and　chamber　temperature　were　increased,　brake　thermal　efficiency　was　first　increased　and　then　decreased　with　the　increase　of　spark　advance.　Advancing　spark　timing　caused　the　increased　flame　development　period,　the　decreased　flame　propagation　period　and　exhaust　temperature.　Cyclic　variation　was　initially　weaken　and　then　deteriorated　after　raising　spark　advance.　HC　and　NOx　emissions　were　reduced　after　retarding　spark　timing.　Spark　timing　had　little　effect　on　CO　emission.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.