As the increase in peroxide value is considered as a sign of deterioration in the quality of oil, possible ways of lowering this value were investigated.  The lowering of the peroxide value can be achieved through reduction, in the chemical sense of the word.  The laboratory results were very conclusive and the industrial implementation led to a marked decrease in peroxide value but it was not possible to reduce it to nil as in laboratory experiments.  The reason lies probably in the lack of intimate contact between the oil and the reducing agent.