Bell pepper (Capsicum annum var. Jupiter) fruit were exposed to 1.5% O2 for 1 to 5 days at 20C to examine whether the low-O2-induced poststorage respiratory suppression (PRS) in whole fruit could be due to limitations in mitochondrial oxidative capacity. Mitochondrial oxidative capacity was not affected after storing bell peppers for 1 day in 1.5 % O2. Extending the storage period from 1 to 5 days in 1.5 % 0, resulted in PRS of CO2 production for about 55 hours after transfer to air, and a marked reduction in the oxidative capacity of isolated mitochondria. Mitochondrial activity was suppressed for 10 hours after transfer to air but, within 24 hours, bad recovered to values comparable to those of mitochondria from fruit stored continuously in air. Storing bell peppers in 1.5% O2 for 5 days resulted in a reduction in the respiratory control (RC), while ADP/O ratios were not affected. The reduction was temporary since the RC attained normal activity after returning bell peppers to air. Cyanide-sensitive cytochrome and CN-insensitive pathways were suppressed after storing fruit in 1.5 % O2 for 5 days. After returning fruit from a low-O2 atmosphere to air, the alternative pathway recovered at a greater rate than the cytochrome pathway.