To　investigate　the　ignition　delay　characteristics　of　DME/H2　mixtures　at　low-to-medium　temperature,　ignition　delay　times　of　lean　DME/H2　mixtures　(hydrogen　mole　fraction　in　the　fuel　mixtures　of　0%,　50%,　60%,　70%,　and　85%)　were　measured　using　a　rapid　compression　machine　in　the　compressed　temperature　range　of　628-858　K　at　compression　pressures　of　12-22　bars,　the　equivalence　ratios　of　0.30-1.00,　and　the　hydrogen　blend　ratio　of　0%-85%.　A　kinetics　model　is　built　to　simulate　the　ignition　process　using　finite　element　software　Chemkin-Pro.　The　results　show　that　the　addition　of　H2　to　DME　mixtures　leads　to　a　nonlinear　increase　in　ignition　delay　time.　The　inhibition　effect　of　H2　addition　is　found　to　be　more　pronounced　at　lower　compression　pressure　with　H2　mole　fraction　of　more　than　60%.　It　is　also　observed　that　lean　DME/H2　mixtures　show　three　stage　heat　release　behaviors　at　lower　equivalence　ratio　of　0.30,　i.e.,　the　first　stage　of　low　temperature　heat　release　(LTHR)　and　the　second　stage　of　high　temperature　heat　release　(HTHR),　and　the　third　stage　of　high　temperature　heat　release.　Meanwhile,　the　three-stage　heat　release　behavior　becomes　weak　as　the　H2　mole　fraction　increases.　Further　chemical　kinetic　analysis　indicates　that　DME　is　mainly　consumed　during　LTHR　and　the　first　stage　of　HTHR　whereas　H2　is　mainly　consumed　during　the　second　stage　of　HTHR.　©　2018,　Editorial　Board　of　Acta　Armamentarii.　All　right　reserved.