In chemistry, an oxidizing agent (oxidant, oxidizer) is a substance that has the ability to oxidize other substances — in other words to accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxide and the halogens.Electron acceptors participate in electron-transfer reactions. In this context, the oxidizing agent is called an electron acceptor and the reducing agent is called an electron donor. A classic oxidizing agent is the ferrocenium ion Fe(C5H5)+2, which accepts an electron to form Fe(C5H5)2. One of the strongest acceptors commercially available is 'Magic blue', the radical cation derived from N(C6H4-4-Br)3.In more common usage, an oxidising agent transfers oxygen atoms to a substrate. In this context, the oxidising agent can be called an oxygenation reagent or oxygen-atom transfer (OAT) agent. Examples include MnO−4 (permanganate), CrO2−4 (chromate), OsO4 (osmium tetroxide), and especially ClO−4 (perchlorate). Notice that these species are all oxides.The dangerous materials definition of an oxidizing agent is a substance that can cause or contribute to the combustion of other material. By this definition some materials that are classified as oxidising agents by analytical chemists are not classified as oxidising agents in a dangerous materials sense. An example is potassium dichromate, which does not pass the dangerous goods test of an oxidising agent.