Effect of temperature and O-2 pressure on the gaseous species produced during the combustion of aluminum is studied using first principles calculations and considering the thermodynamics of the gas phase equilibrium composed of Al, O-2, AlO, Al2O, AlO2, Al2O2 and Al2O3. AlO partial pressure dominates all the range of 02 pressures/temperatures. AlO2 is the second most abundant species at low to intermediate temperatures (1200-1727 degrees C) and Al2O at higher temperatures (similar to 3300 degrees C). Al2O and Al2O2 are stable when ionized into mass spectrometer. Al2O3, Al2O and, to a lesser extent AlO, will decompose, hindering their quantitative observation using this technique. 2016 Elsevier B.V. All rights reserved.