Aqueous compositions of hexanal, an inhibitor of phospholipase D, has been shown to enhance the shelf life and quality of fruits and vegetables. In the present study, sweet bell pepper fruit were exposed to hexanal vapor and its effect on quality attributes, shelf-life, and antioxidant enzyme activities were evaluated during storage at 7 day intervals for 21 d. Peppers subjected to hexanal vapor treatments (0.005, 0.01, and 0.02%, w/w) showed a significant (p < 0.05) delay in ripening process and preservation of postharvest qualities than untreated peppers, even at 21 d of storage. Treated fruit were characterized by increased firmness, a reduction in physiological water loss and lower electrical conductivity than control fruit, which indicated better membrane preservation. These treatments also resulted in an increase in the levels of antioxidant enzyme activities, specifically that of superoxide dismutase, catalase, glutathione reductase and guaiacol peroxidase. Evidences from the present study indicate that postharvest hexanal vapor treatment at optimal levels can effectively enhance the quality and shelf life of sweet bell peppers.