AbstractThe oxidation kinetics of malachite green (MG) with peroxydisulphate ion (PDS) were investigated by monitoring the absorbance change at 618 nm, in aqueous solutions under buffered and unbuffered conditions. Under both conditions, the reaction had first order dependence on reductant and a fractional order (one half) dependence on the oxidant. The stoichiometric ratio between MG and PDS was 1:2. The reaction had a negative salt effect. Reaction rates were enhanced under both high or low pH relative to neutral conditions. A plausible mechanism is proposed.