Cobalt hangman corrole, bearing beta-octafluoro and meso-pentafluorophenyl substituents, is an active water splitting catalyst. When immobilized in Nafion films, the turnover frequencies for the 4e(-)/4H(+) process at the single cobalt center of the hangman platform approach 1 s(-1). pH dependence of the water splitting reaction suggests a proton-coupled electron transfer (PCET) catalytic mechanism.