The results of an x-ray photoelectron loss spectroscopy (XPLS) study of several wide band gap aluminum compounds are presented here. XPLS is a new application of x-ray photoelectron spectroscopy involving the determination of the energy separation, ΔE, between a particular core photoelectron peak and its principal loss peak. The materials investigated here are sputter deposited thin film Al-nitride and oxide, and bulk single crystal α-alumina. It is not possible to distinguish between these materials on the basis of the chemical shift in the binding energy of the A12p and A12s photoelectrons (Siegbahn shift). The results show that XPLS can be used to distinguish between these materials. ΔE in Al-oxides and nitride differs by several eV and is independent of sample charging. Comparison with ΔE calculated using a free electron gas model is made and related to the plasmon nature of ΔE.