Ru (bpy) 32+ and a suitable organic acid or salt (eg, C2042") is described. The system produces quite bright emission and may be useful in practical eel devices. The system is an example of a coupled chemical reaction15 with the observation of light emission as a probe of the reaction mechanism. The Ce3+-oxalate system (or one with another organic acid or salt) provides a unique electrochemical system for carrying out a reduction under oxidizing conditions at the electrode surface (an “anodic or oxidative reduction”). Upon applying a sufficiently positive potential to an oxidized Pt (or carbon) electrode, one promotesthe one-electron oxidation of the acid by the Ce4+, creating an intermediate (eg, C02~·) which is a strong reducing agent. This intermediate has a sufficiently long lifetime in aqueous solution to be able to reduce other molecules in the solution (eg, Ru (bpy) 33+ in the light-em-itting reaction in 1.0 Mh2s04). This system can therefore, in principle, be used for electroreductions in aqueous solution under conditions of mild anodic potential and at a Pt electrode.