Understanding and domination of energy is one of the goals the human mankind has always followed, but it has never had as much importance as it has nowadays. At present, more of 90 % of the total amount of energy support in the world is provided by combustion [Warnatz et al. (2006)]. Due to the pollution problems and restrictions this process has attached, the search of alternative fuels, i.e. those which can be classified as renewable, less contaminant or cheaper and that do not proceed from petroleoum, is the order of the day [Reyes Gonzalez et al.]. Not only alternative energy sources for producing electricity but also new fuel technologies for propulsion use are being deeply investigated. One of the most extended alternative fuel for mobility use is methane (CH4), the simplest alkane, due to the fact that is one of which emit less contaminant substances to the atmosphere, is abundant and economical [Zinner (2008)]. Its oxidation characteristics can be adjusted quite easily by means of adding trace amounts of other fuels [Spadaccini and Colket III (1994)]. One of the best suited additives for achieveing this is the dimethyl ether or DME (C2H6O), because is not only a good ignition enhancer for propulsion systems and internal combustion engines but also reduces the particulate and NOX emissions [Mittal et al. (2008a)]. Furthermore, its physical properties are similar to those of Liquified Petroleum Gases (LPG), so dimethyl ether can be stored and distributed using the already established LPG infrastructures [Mittal et al. (2008a)]. In this study an important feature of the fuels, the ignition-delay time, is widely investigated using methane in combination with dimethyl ether as the fuel mixture basis, with the aim of determine the differences regarding the variations in the composition and physical conditions of the mixture.