A reducing agent (also called a reductant or reducer) 's the element or compound in a redox (reduction-oxidation) reaction (see electrochemistry) that reduces another species. In doing so, it becomes oxidized, and's therefore the electron donor in the redox. For example consider the following reaction: » [Fe(CN)6]4- + 1/2 Cl2 → [Fe(CN)6]3- + Cl- The reducing agent in this reaction's ferrocyanide: it donates an electron, converting to ferricyanide, simultaneous with the reduction of chlorin… (More on Reductant)