First-principles calculations that are based on spin-unrestricted density functional theory and the generalized gradient approximation have been used to study the adsorption of nitromethane and 1,1-diamino-2,2dinitroethylene molecules on the AI(1 1 1) surface. The calculations employ (3 x 3) aluminum slab geometries and three-dimensional periodic boundary conditions. On the basis of these calculations, we have determined that both dissociative and nondissociative adsorption mechanisms are possible, depending on the molecular orientation and the particular surface sites involved. In the case of dissociative chemisorption, O-atom abstraction by Al surface atoms has been determined to be the dominant mechanism. The dissociated o atom forms strong Al-O bonds with the neighboring Al sites around the dissociation sites. In addition, the radical species obtained as a result of O-atom elimination remains bonded to the surface. In some instances, both O atoms of the nitro group dissociate and oxidize the aluminum surface. Finally, for the case of nondissociative adsorption, various N-C-Al bridge-type bonding configurations can be formed. On the basis of the data provided from these studies, it can be concluded that oxidation of the aluminum surface readily occurs, either by partial or complete dissociation of the O atoms from the NO2 group.