The WO 3 surface catalyst offers the acceleration of the conversion of water into oxygen and protons. In this work, we study the oxygen evolution reaction (OER) and H 2 O 2 formation as competitive reactions on the (001) WO 3 surface using stateof-the-art simulation techniques: metadynamics and ab initio molecular dynamics. We calculate the free energy surfaces of the OER and H 2 O 2 formation. This research paves the way for further investigation and improvement of efficient catalysts for water oxidation catalysis.