This　paper　studied　the　effect　of　spark　timing　on　combustion　and　emissions　characteristics　of　a　hydrogen-enriched　methanol　engine.　The　experiment　was　performed　on　a　four-cylinder　gasoline　engine　equipped　with　an　electronic　controlled　hydrogen　port-injection　system.　The　engine　speed　was　kept　at　1400　rpm　and　the　manifolds　absolute　pressure　was　kept　at　61.5　kPa　with　an　excess　air　ratio　of　1.20.　The　hydrogen　volume　fractions　in　the　total　intake　were　kept　at　0,　1.5%　and　3%,　respectively.　The　spark　timings　for　each　specified　hydrogen　addition　level　were　varied　from　18　to　46　degrees　CA　before　top　dead　center　with　steps　of　2　CA.　The　test　results　showed　that　the　indicated　thermal　efficiency　was　first　increased　and　then　decreased　with　the　increase　of　spark　advance.　With　increase　of　spark　advance,　flame　development　period　was　prolonged　whereas　the　flame　propagation　period　was　shortened.　The　coefficient　of　variation　in　indicated　mean　effective　pressure　was　first　decreased　and　then　slightly　increased　with　the　advance　of　spark　timing.　HC　and　CO　emissions　were　decreased　after　hydrogen　addition.　NOx　from　the　hydrogen-blended　engines　could　be　reduced　through　retarding　the　spark　timing.　Copyright　(C)　2015,　Hydrogen　Energy　Publications,　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.