In chemistry, an oxidizing agent (oxidant, oxidizer), or oxidising agent (oxidiser) 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.

In one sense, an oxidizing agent is a chemical species that undergoes a chemical reaction in which it gains one or more electrons. In that sense, it is one component in an oxidation–reduction (redox) reaction. In the second sense, an oxidizing agent is a chemical species that transfers electronegative atoms, usually oxygen, to a substrate. Combustion, many explosives, and organic redox reactions involve atom-transfer reactions.

 

Note:   The above text is excerpted from the Wikipedia article Oxidizing agent, which has been released under the GNU Free Documentation License.