Investigation of the effects of aluminum on self-propagation and explosive combustion synthesis of MoSi 2 Silicides are a new promising group of materials which have gained a lot of interest for structural applications in aerospace and energy industries due to their unique properties including high melting point, relatively low density and good corrosion resistance. In this study, effect of the oxidation of aluminum particles on the formation of MoSi 2 through combustion synthesis process was investigated. For this purpose, samples with 0, 4, 7 and 10 wt% Al were prepared by pressing mixtures of molybdenum and silicon powders under a pressure of 175 kg.cm -2 . In order to evaluate the effect of aluminum addition on process procedure and parameters, self-propagation hight temperature (SHS) and thermal explosive (TE) combustion synthesis tests were performed under air and argon atmospheres. Phase and structural characterization of process products were done using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Optical microscope images along with Clemex image analyzing software were used to determine percentage of porosity in the synthesized samples. Furthermore, in order to study the reaction rate, progress of combustion wave front in self-propagating synthesized samples were recorded using a Canon camcorder. The results obtained reveals that aluminum dissolves in MoSi 2 by occupying Si sites via substitution mechanism causing the transformation of tetragonal lattice to hexagonal structure. In addition, due to the endothermic nature of tetragonal?hexagonal transformation, temperature and velocity of combustion front are reduced. In self-propagating reaction, aluminum acts as diluent and aluminum oxide has no role in SHS process. I thermal explosive process, aluminum and silicon form eutectic and non-eutectic melts which lead to a decrease in temperature and time of process initiation. Also, to investigate the influence of oxidation of aluminum powder on combustion synthesized MoSi 2 , oxidation tests were performed on samples containing 0 and 10 wt% aluminum for 12 hours with 2-hour cycles using a tube furnace. It is observed that oxidation of aluminum free samples occurs in the temperature range of 400-600 °C; this oxidation, often known as pest, results in collapse of powder sample as well as changing of its color from black to green. However, for sample containing 10 wt% aluminum, oxidation does not happen in this temperatures and no significant color change is observed for sample; in fact, it can be concluded that aluminum prevents the oxidation of MoSi 2 . Also, according to XRD analysis data at 850 °C, it can be concluded that aluminum incorporated in hexagonal structure forms a protective Al 2 O 3 film which hinders oxidation of MoSi 2 . Therefore, aluminum effectively improves the low temperature oxidation of MoSi 2 and prevents so called pest corrosion. Keywords: Combustion synthesis process, MoSi 2 , Aluminum, Oxidation