Cactaceae are widely present in the semiarid region of Northeastern Brazil. Pilosocereus gounellei, popularly known as Xique-xique, is found in the driest regions of the Caatinga biome, and although there is little knowledge about its constitution, it is among the species used in feeding animals and the population of this region. This study aimed to evaluate the nutritional composition and antioxidant potential of Xique-xique. Thus, the following parameters were evaluated: pH; water activity; humidity; total solids; carbohydrates; proteins; lipids; ash; acidity; mineral content; phenolic compounds and activity in sequestering DPPH radicals; ABTS; and FRAP. For this purpose, Xique-xique cladodes were cut and separated into three experimental groups: Vascular Cylinder (VC), Central Stem (CS) and Vascular Cylinder + Central Stem (VCCS). Differences (p<0.05) were observed among the groups in most of the analyzed variables, with the exception of pH, water activity and sugar content, with glucose, fructose and sucrose being among the sugars present in the composition. The following values were determined: acidity (0.09±0.02%), lipids (5.98±0.04 g/100 g) and carbohydrates (75.76±0.01 g/100 g) in the CS; and humidity (0.98±0.01 g/100 g), proteins (8.39±0.02 g/100 g) and ashes (34.07±0.04 g/100 g) in the VC. Still, in the VC, representative amounts of calcium (2493.00±95.00 mg/100 g), magnesium (3123.00±36.00 mg/100 g), selenium (0.05±0.00 mg/100 g) and zinc (7.78±0.11 mg/100 g), as well as soluble fiber (14.83±0.17 g/100 g) and insoluble fiber (40.18±0.38 g/100 g) contents were found in the CS. The content of phenolic compounds (0.22±0.01 mg GAE/g) and antioxidants (ABTS) (22.15±3.02 RSA%) were higher in the CS, and the antioxidants dosed through the FRAP methodology presented higher results in the VC (200.63±4.04 µg Trolox/g). From this study, greater knowledge about the physicochemical and nutritional composition of Xique-xique was achieved, thus being able to provide nutrients in human and animal nourishment.