Aluminum continues to be of great interest as a fuel in propellant formulations. Quantitative modeling of the multistep ignition and combustion processes requires considerable thermodynamic and kinetic data, some of which are currently not available or not reliable. We have accordingly carried out CBS-QB3 calculations of the enthalpies and free energies, at 298 and 2000 K, of atoms and molecules that are likely to be involved in the combustion of aluminum-based propellants. These have been used to find the respective heats of formation, as well as the heats of reaction and equilibrium constants for numerous possible steps in the ignition/combustion processes. In a few instances, we also determined transition states and activation barriers. Certain interesting aspects of the results are discussed in greater detail.