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 Mn 3+ in the system. Effect of the concentration of the constituents as well as the effect of temperature are discussed. © 1978 Indian Academy of Sciences.