The chemical stability of the Li-O 2 battery components (cathode and electrolyte) in contact with lithiumperoxide (Li 2 O 2 ) was investigated using X-ray photoelectron spectroscopy (XPS). XPS is a versatile method to detect amorphous as well as crystalline decomposition products of both salts and solvents. Two strategies were employed. First, cathodes including carbon, α‑MnO 2 catalyst, and Kynar binder (PVdF-HFP) were exposed to Li 2 O 2 and LiClO 4 in propylenecarbonate (PC) or (tetraethylene glycol dimethyl ether) TEGDME electrolytes. The results indicated that Li 2 O 2 degrades TEGDME to carboxylate containing species and that the decomposition products in turn degraded the Kynar binder. The α‑MnO 2 catalyst was unaffected. Second, Li 2 O 2 model surfaces were kept in contact with different electrolytes to investigate the chemical stability, and also the resulting surface layer on Li 2 O 2 . Further, the XPS experiments revealed that the Li salts LiPF 6 , LiBF 4 , and LiClO 4 decomposed to form LiF or LiCl together with P-O or B-O bond containing compounds when exposed to Li 2 O 2 . PC decomposed to carbonate and ether based species. The degradation of the electrolytes increased from short to long exposure time indicating that the surface layer on Li 2 O 2 became thicker by increasing time. Overall, it was shown that a mixture of ethylene carbonate and diethyl carbonate (EC/DEC) is more robust in contact with Li 2 O 2 compared to PC.