Li-O2 batteries (LOBs) operating via LiOH chemistry have attracted increasing interest due to the higher stability of LiOH in organic electrolytes, compared to Li2O2. Several catalysts have been shown to promote the formation of LiOH during discharge. However, LiOH has been difficult to reoxidize to form oxygen on charging. Here, we report that, in the presence of water, the catalyst Co3O4 promotes the formation of LiOH on discharge via a 4 e-/O2 process with few side reactions, forming large (001) facet-exposed LiOH flakes. Hydroperoxide LiOOH was detected as a potential discharge intermediate. During charge, O2 evolution was detected along with LiOH decomposition up to 3.9 V; at higher voltages, products from parasitic reactions can be detected. This work provides new insights into the role of solid catalyst for LiOH chemistry in LOBs, which will promote the development of reversible and long-lasting LiOH-based LOBs.