This　paper　investigated　the　effect　of　hydrogen　addition　on　enhancing　the　performance　of　a　methanol　engine　at　part　load　and　lean　conditions.　The　experiment　was　conducted　on　a　modified　spark-ignited　engine　equipped　with　an　adjustable　dual-fuel　injection　system.　The　engine　was　run　at　an　engine　speed　of　1400　rpm　with　two　hydrogen　volume　fractions　in　the　intake　of　0%　and　3%.　The　test　results　illustrated　that　the　engine　cyclic　variation　was　eased　and　the　brake　thermal　efficiency　was　enhanced　after　the　hydrogen　blending.　Besides,　the　hydrogen　enrichment　was　effective　on　reducing　the　flame　development　and　propagation　periods.　HC　and　CO　emissions　were　generally　reduced　after　the　hydrogen　blending.　NOx　emissions　from　the　hydrogen-blended　methanol　engine　could　be　dropped　to　a　low　level　when　the　engine　was　run　under　high　excess　air　ratios.　Copyright　(C)　2013,　Hydrogen　Energy　Publications,　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.