The surface of six different grades of commercial sub-micron high purity α-Al₂O₃ powders produced by two different processes, in-situ chemical vapor deposition (“A” powders), and hydrolysis of aluminum alkoxide (“B” powders) methods, were evaluated by temperature programmed desorption mass spectrometry (TPDMS) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Desorption of CO₂ molecules was detected for all the powders, but the quantity was greater for the “B” powders than the “A” powders. The maximum of the CO₂ desorption peak was in the range of 230-270°C for all powders. The desorbed CO₂ peak was considered to evolve from adsorbed CO₂ molecules forming hydrogen carbonyl groups through interaction with the Al^IV-OH groups on the α-Al₂O₃ surfaces. The DRIFT spectra of the powders heated at 700°C under vacuum confirmed a larger population of Al^IV-OH groups on the surface of the “B” powders. The present study clearly demonstrates the presence and quality of the Al^IV on the surface of α-Al₂O₃ powders and the effect of the type of manufacturing process on their proportion.