The young succulent stems of the prickly pear cactus ( Opuntia ficus-indica and Opuntia inermis), a specialty vegetable, were harvested at two stages of development (10 and 20 cm long) and stored at 5, 10, 15 and 20°C for up to 30 days. Cactus stems of both species maintained their visual quality for 3 weeks at 5 and 10°C. Longer term storage at 5°C resulted in occasional development of surface discoloration on stems of O.ficus-indica. Small stems had higher carbon dioxide production rates than large stems, approximately 60 l CO 2 g −1h −1 and 25 l CO 2 g −1h −1 1 day after harvest decreasing to 40 l CO 2 g −1h −1 and 20 l CO 2 g −1h −1 after 10 days at 20°C and 10°C, respectively. Ethylene production rates were low, averaging 0.2 nl g −1h −1 at 20°C. The titratable acid content of cactus stems was affected by time of day of harvest and the subsequent storage temperature. Small stems were crassulacean acid metabolism-inactive, whereas large cactus stems showed diurnal fluctuations in acid content (0.94% at 08:00 h and 0.47% at 18:00 h). Storage of large cactus stems for 9 days at 10, 15 and 20°C resulted in a decreased acid content, whereas storage at 5°C resulted in steady or increased acid content. Longer term storage resulted in decreased acid content at all storage temperatures, but the rate of decrease was less at low temperatures.