Synergic effect of fuels with different ignition properties on engine combustion process has been followed with interest recently. To further reveal their interaction mechanism during combustion, numerical simulations have been performed in this study, addressing hydrogen addition effect on a reaction front propagation in negative temperature coefficient (NTC) affected auto-igniting dimethyl ether (DME) and air mixture. Firstly, homogeneous auto-ignition responses show that auto-ignition delay is obviously retarded in NTC regime while advanced beyond the regime as hydrogen addition due to the decreasing heat release during cool flame ignition and increasing heat release during final hot ignition. Chemical analysis indicates that the variation in this polarized heat release distribution is attributed to NTC-affected chemistry and total equivalence ratio. Secondly, the results of a reaction front propagation in non-reacting mixture show that the NTC-affected reaction front is also influenced by hydrogen addition, characterized as the delayed cool flame ignition and increasing maximum temperature gradient of a reaction front as well as linearly increasing reaction front speed. Finally, when the reaction front propagates in NTCaffected partially auto-igniting mixture, it shows that both reaction progress and hydrogen addition significantly increase transport-controlled deflagration front speed. However, contrary to the reaction progress, hydrogen addition depresses NTC-affected cool flame and combustion regime transitions from transport-controlled deflagration towards reaction-controlled spontaneous ignition. And meanwhile, slight flame acceleration is also observed when the reaction progress crosses over the corresponding temperature region dominated by NTC chemistry. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.