An iodometric method for the rapid microdetermination of organic peroxides, utilizing electrochemical reduction in the iodine-iodide system, has been developed. After complete reaction between peroxide and iodide in an acidic semi-aqueous medium the iodine produced is reduced at a rotating platinum electrode, at constant potential. Electronic integration is used. Organic peroxides of different reactivities have been analysed by making use of the increased rate of reaction at elevated temperatures. Accurate and precise results were obtained for samples at the 1-mg level and the total time of analysis varied from 8 to 20 min, depending on reactivity.