Certain salient features of the oscilliatory reaction in the iodate-hydrogen peroxide-manganese sulphate-malonic acid system are presented. Oscillations were followed by recording the potential developed at a platinum electrode. Reproducibility of the results in such a complicated system is established. Evidence is provided for the periodic formation of Mn³⁺ in the system. Effect of the concentration of the constituents as well as the effect of temperature are discussed.

The oscillation characteristics of the iodate systems (Briggs-Rauscher reaction) and the bromate system (Belousov-Zhabotinskii reaction) with ethylacetoacetate show that the species responsible for the oscillations in these two systems are different. This arises from a large value of the exchange current density for Pt/I₂/I⁻. The inclusion of ferroin in an uncatalysed bromate system (ubs) leads to a switchover to a new oscillatory phase, catalysed bromate system (cbs). Oscillation inubs is caused by a periodic change in the concentration of bromine. The switchover in oscillation characteristics on the addition of ferroin results from the value of the exchange current density for Pt/Fe(III)/Fe(II) being larger than Pt/Br₂Br⁻.