Aims: The aim of this work was to evaluate the physico-chemical and biochemical attributes and the postharvest conservation of 'Thomson' [Hylocereus undatus (Haw.) Britton and Rose] under different storage temperature during storage.
 Study Design: The experimental design used was completely randomized with three treatments and four replications of four fruits/repetition.
 Place and Duration of Study: The experiment was carried out with 'Thomson' pitaya harvested in an organic orchard located in the municipality of São Miguel do Oeste, Santa Catarina, Brazil, during the 2018/2019 harvest.
 Methodology: The storage temperature treatments evaluated after postharvest were 23°C, 9°C and 4°C. The storage of the fruits was carried out in chambers with biochemical oxygen demand (BOD). The fruits were evaluated at different dates (7, 14, 21, 28 and 35 days) during storage.
 Results: At 7 days of storage, the fruits stored at 23 °C showed higher values of mass loss, lipid peroxidation, pulp browning and activity of peroxidase (POX) and ascorbate peroxidase (APX) enzymes, as well as reductions in soluble solids contents (SS), titratable acidity (TA) and pulp firmness. At 14 and 21 days, storage at 9°C showed reductions in lipid peroxidation and pulp browning, as well as higher vitamin C contents and lighter and more intense skin color. Also, at 21 days, the fruits stored at 9°C showed higher values of SS, AT and pulp firmness, and reductions in mass loss and in the activity of POX and APX enzymes.
 Conclusion: It is concluded that the storage of 'Thomson' pitayas at 23 °C provides a short postharvest period and early senescence of the fruits, while the temperature of 9 ºC increases the shelf life of the fruits and proves to be quite efficient in the conservation of the attributes of quality. The storage at 4°C is not recommended due to high internal browning, oxidative stress and loss of quality attributes.