In peach, which is a climacteric fruit species, the fruit deteriorates rapidly at post harvest with the increase in ethylene production and respiration rate during ripening, and significant changes occur in quality properties and antioxidant activity. In the study, the effect of melatonin applications at different doses (0, 0.10, 0.25, 0.50 and 1.00 mM) at postharvest on fruit quality characteristics and biochemical content during cold storage was determined. The increased weight loss and decay rate with the prolongation of the cold storage period were lower in melatonin-treated fruit and varied depending on the application concentration. Melatonin application was effective in maintaining fruit flesh firmness, but application concentration had no effect. An increase in soluble solids content (SSC) ratio and a decrease in acidity occurred during storage, and changes in SSC and titratable acidity ratios were lower with melatonin application. In general, melatonin application was effective in maintaining the concentration of organic acids, but this effect varied depending on the concentration and compound. As a result, it was concluded that 0.25 mM melatonin application can be used to maintain the postharvest fruit quality of peach.