Dimethyl　ether　(DME)　seems　to　be　a　potential　approach　for　improving　the　cold　start　performance　for　spark-ignited　(SI)　engines.　In　this　paper,　the　cold　start　performance　of　an　SI　engine　fueled　with　pure　DME　was　experimentally　investigated　and　compared　with　that　of　the　original　SI　gasoline　engine.　The　engine　was　successfully　cold　started　with　pure　DME　and　pure　gasoline,　respectively.　The　test　results　demonstrated　that,　the　fuel　energy　flow　rate　of　the　SI　DME　engine　was　only　30%　of　that　of　the　original　SI　gasoline　engine　whereas　the　imep　(indicated　mean　effective　pressures)　of　the　SI　DME　engine　was　effectively　enhanced　in　the　first　5　cycles.　The　SI　DME　engine　had　a　shortened　flame　development　period　compared　with　the　original　SI　gasoline　engine.　Meanwhile,　the　HC　emissions　were　averagely　decreased　by　80%　under　the　pure　DME　mode.　The　instantaneous　CO　and　NOx　emissions　from　the　SI　DME　engine　were　slightly　increased　in　the　initial　seconds　after　the　onset　of　cold　start　and　then　markedly　reduced　compared　with　those　from　the　original　SI　gasoline　engine.　In　view　of　the　above,　starting　an　SI　engine　with　pure　DME　could　improve　the　combustion　and　emissions　performance.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.