Reduce reactions or oxidation reduction reactions in which the oxidation states of atoms change. Acid based reactions, hydrolysis reactions and isomerization reaction are very common examples of some other types of chemical reactions. Now, note that a certain reaction can be labeled as more than one. In other words, let's look at the following decomposition reaction. This decomposition reaction is also an oxidation reduction reaction because our O gets oxidized while our H gets reduced. In other words, in this molecule, our O has an oxidation state of negative two.