Significance A long-standing goal in science seeks to understand and mimic photosynthesis. The water oxidation half-reaction of photosynthesis can be mimicked with bulk metal oxide catalysts, although with only modest efficiencies. Thus, there is immense effort to learn how bulk oxides operate and to identify critical mechanistic principles that can guide the design of improved catalysts. A functional molecular analogue of cobalt oxide water oxidation catalysts, the Co ₄ O ₄ cubane, has provided a plethora of mechanistic information, although its instability in solution has prevented thorough characterization of key catalytic intermediates. We now show that a rigid coordination network greatly stabilizes this Co ₄ O ₄ catalyst by providing a supporting “matrix,” immobilizing and preserving the key reactive intermediate to enable structural and catalytic characterization.