The reaction of 2-methylindole with hexacyanoferrate(III) in alkaline media to produce the corresponding 2-methylindolin-3one has been studied at constant temperature and ionic strength. The reaction followed first order kinetics with respect to [2methylindole], [OH -] and [Fe(CN)6 3-]. The effects of added electrolytes, potassium hexacyanoferrate(II), relative permitivity and temperature have also been studied. On the basis of experimental observations, a probable reaction mechanism has been proposed.