Methanol　is　a　promising　alternative　fuel　for　the　spark-ignition　engines.　This　paper　experimentally　investigated　the　performance　of　a　hydrogen-blended　methanol　engine　at　lean　and　various　load　conditions.　The　test　was　conducted　on　a　four-cylinder　commercial　spark-ignition　engine　equipped　with　an　electronically　controlled　hydrogen　port　injection　system.　The　test　was　conducted　under　a　typical　city　driving　speed　of　1400　rpm　and　a　constant　excess　air　ratio　of　1.20.　Two　hydrogen　volume　fractions　in　the　intake　of　0　and　3%　were　adopted　to　investigate　the　effect　of　hydrogen　addition　on　combustion　and　emissions　performance　of　the　methanol　engine.　The　test　results　showed　that　brake　thermal　efficiency　was　improved　after　the　hydrogen　addition.　When　manifolds　absolute　pressure　increased　from　about　38　to　83　kPa,　brake　thermal　efficiencies　after　the　hydrogen　addition　were　increased　by　6.5%　and　4.2%.　The　addition　of　hydrogen　availed　shortening　flame　development　and　propagation　periods.　The　peak　cylinder　temperature　was　raised　whereas　cylinder　temperature　at　the　exhaust　valve　opening　was　decreased　after　the　hydrogen　addition.　The　addition　of　hydrogen　contributed　to　the　dropped　hydrocarbon　and　carbon　monoxide.　However,　nitrogen　oxides　were　slightly　raised　after　the　hydrogen　enrichment.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.