ABSTRACTMeasurements of linoleate oxidation catalyzed by nonheme iron or metmyoglobin (MetMb) have been frequently used as a model systems approach to investigate the mechanism of lipid peroxidation in meat. The objective of this study was to determine systematically the effects of Tween 20 (a nonionic surfactant), phosphate (a buffer component), MetMb (a heme iron catalyst), and Fe2+‐EDTA (a nonenzymic nonheme iron catalyst) on linoleate oxidation. The oxidation was determined by polarographic measurements of oxygen tension. Tween 20 slightly enhanced MetMb catalysis of linoleate oxidation at pH 7.6 and markedly increased Fe2+‐EDTA catalysis at pH 5.6. Phosphate accelerated MetMb catalysis but inhibited Fe2+‐EDTA catalysis. The rate of MetMb catalysis was not proportional to MetMb concentration even within a narrow range whereas the rate of Fe2+‐EDTA catalysis increased linearly with the concentration of Fe2+‐EDTA (1:1) complex. Appropriate model conditions for the two catalytic systems have been proposed for effective utilization of the model systems in future research. The choice of Fe2+‐EDTA as a nonenzymic nonheme iron catalyst has been explained based on its catalytic activity and practical considerations in the use of polarographic measurements of oxygen uptake for linoleat