another species undergoes reduction. An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. ... The formation of hydrogen fluoride is an example of a redox reaction. We can break the reaction down to analyze the oxidation and reduction of reactants.Redox reactions are matched sets: if one species is oxidized in a reaction, another must be reduced. Keep this in mind as we look at the five main types of redox reactions: combination, decomposition, displacement, combustion, and disproportion.