A new pH oscillator has been discovered involving the system of NaClO2, Na2SO3, and H2SO4 in a continuous flow stirred tank reactor (CSTR). While ClO2- serves as an oxidant in numerous systems exhibiting nonlinear dynamical behavior, this is the first reported chlorite-based pH oscillator. Large-amplitude oscillations in pH and potential of a platinum electrode were observed over a rather narrow concentration range. Complex dynamical behavior also was observed, including aperiodic oscillations, bistability between steady states, bistability between steady state and oscillatory state, bursting, a possible third steady state, and damped oscillations in batch. Autocatalytic oxidation of HSO3- by ClO2- is a major source of positive feedback in H+. A fast Cl+-transfer reaction between HOCl and SO32- is an important source of negative feedback. Oscillations were also obtained in the presence of Na2CO3, with the dehydration reaction of H2CO3 providing additional negative feedback. Models are proposed to account for observed behavior using computer simulations. Comparisons are made to the ClO2--I- and ClO2-I- oscillating systems, as well as to the general model for chlorite-based chemical oscillators proposed by Rabai and Orban. A possible mechanism for chemical coupling is proposed.