Among the many environmental problems affecting human health and safety, air and water pollution affect millions of people globally. HO is a clean oxidant for production of hydroxyl radicals (OH) that decomposes nearly all organic pollutants. However, electro-Fenton (EF) strategies for producing HO are still unsatisfactory because of intermittent production, negative decomposition, and the wide use of pure O or/and proton exchange membranes. Here we report a wood-derived solid ionic conductor (WSIC) to propose a solid EF strategy for continuous cathodic production of giant HO using only air and water. Effective activation of HO by FeOCl generates OH, which continuously degrades aqueous (99.9%, Rhodamine B) or mineralizes gaseous toluene into CO and HO at room temperature. Our findings are a fundamental step toward development of next-generation of advanced oxidation processes that are sustainable and cost effective.