Ignition　delays　of　dimethyl　ether　and　hydrogen　(DME/H-2)　mixtures　(hydrogen　blending　ratio　ranging　from　0%　to　60%)　were　measured　in　a　rapid　compression　machine　at　compressed　temperatures　ranging　from　655　to　810　K　and　compressed　pressures　from　16.9　to　24.5　bar　with　an　equivalence　ratio　range　of　0.8-1.6.　Experimental　measurements　are　compared　with　results　from　numerical　simulations　using　the　NUIG　Mech_56.54　mechanism　and,　in　general,　a　good　agreement　is　obtained.　The　first-stage　ignition　delay　of　DME/H2　mixtures　proves　to　be　insensitive　to　compressed　pressure　and　equivalence　ratio,　whereas　the　total　ignition　delay　decreases　distinctly　with　the　increase　of　compressed　pressure　and　equivalence　ratio,　especially　in　the　negative　temperature　coefficient　(NTC)　region.　Moreover,　the　simulation　results　show　that　the　NTC　region　shifts　to　a　higher　temperature　when　compressed　pressure　is　increased.　Increasing　the　equivalence　ratio　enhances　the　overall　system　reactivity　but　does　not　significantly　change　the　temperature　range　of　the　NTC　region.　Both　first-stage　and　total　ignition　delay　increase　with　the　increase　of　hydrogen　blending　ratio.　The　total　ignition　delay　as　a　function　of　hydrogen　blending　ratio　increases　nonlinearly,　and　the　effect　of　hydrogen　addition　becomes　more　prominent　in　the　NTC　region　and　at　60%　hydrogen　blending　ratio.　Kinetic　analysis　indicates　that　hydrogen　addition　consumes　OH　radical　and　inhibits　DME　low-temperature　oxidation.　More　fuel　molecules　undergo　chain　propagation　reaction　subsequently,　leading　to　the　decrease　of　heat　release　and　radicals　generated　during　the　first-stage　ignition　and　longer　total　ignition　delay.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.