MagnesiumMagnesium (Mg) and Mg alloy powders are generally difficult to sinter at atmospheric pressure in inert atmosphere purportedly due to the presence of powder particle surface oxide layers. To better understand sintering of Mg and Mg alloy powdersSintering of Mg and Mg alloy powder, x-ray photoelectron spectroscopy (XPS) was performed to characterize the surface chemistry of gas atomized powders of pure Mg and Mg alloys AZ91D and WE43. These results are used to quantitatively determine the surface chemistry and surface chemistry as a function on depth of these powders. Additionally, equilibriumEquilibrium thermodynamicThermodynamic modeling of these Mg/Mg alloys exposed to part per billion quantities of oxygen are presented for relative comparison to experimental results. These results and the analysis of these results are intended to improve sintering of Mg and Mg alloy powderSintering of Mg and Mg alloy powder materials through more quantitative knowledge of powder surface chemistry.