The purpose of this research work is to determine the physicochemical characteristics of the juice of the mature fruit of Physalis peruviana L. "aguaymanto" and the reducing action on the ferric ion. The fruit of Physalis peruviana L. was collected in the province of Cajabamba, the juice was obtained with a liquefier extractor. Analyzes of the organoleptic characteristics, density, pH, refractive index, acid number, total soluble solids and solubility in ethanol were carried out. Also, the reducing action on the ferric ion was determined by the modified method of Oyaizu M., using as a standard the gallic acid and preparing working samples of the juice at concentrations of 200, 400, 600, 800 and 1000 mg/mL; 1 mL of the working sample was measured by mixing with 5 mL of phosphate buffer, at pH 6,6 and with 5 mL potassium ferricyanide [K3Fe (CN) 6] at 1% and after an incubation period of 20...