The mangosteen peel (Garcinia mangostana L.) contains anthocyanin pigments, which has an important role in coloring. This study aims to determine the physicochemical properties of mangosteen peel extract (Garcinia mangostana L.) with two methods, which is an examination with UV-Vis and FTIR spectrophotometry. Then the extract was characterized, identified, and analyzed for its stability against temperature, pH, and applied as a coloring agent in the formulation of pharmaceutical preparations (tablets). The results showed that the yield of mangosteen peel extract obtained 13.0975 %, drying losses 5.2822 %, total ash content 14.488 %, acid insoluble ash content 0.684 %, water-soluble extract content 29.58 %, extract content dissolved in ethanol 37.78 %, total anthocyanin content with λmax = 367 nm which is = 9.58 mg / 100 g and with λmax = 289 nm which is = 52.43 mg / 100 g. In this study, the anthocyanin pigment content in mangosteen peel extract cannot be used as an alternative to natural dyes for pharmaceutical preparations (tablets).