Herbal therapy, an oldest kind of medicare known to humans and involves the use of entire plant or plant part, for the treatment of various debilitating diseases or to support good health Natural herbs were extensively used for the treatment and prevention of various ailments since ancient times. Guava (Psidium guajava Linn.) Family Myrtaceae is important plant used traditionally for medicinal purpose Psidium guajava, is an important food crop and medicinal plant in tropical and subtropical countries is widely used like food and in folk medicine around of the world The pharmacological actions and the medicinal uses of aqueous extracts of guava leaves in folk medicine include the treatment of various types of gastrointestinal disturbances such as vomiting, diarrhea, inhibition of the peristaltic reflex, gastroenteritis, spasmolytic activity, dysentery, abdominal distention, flatulence and gastric pain. This study focuses on Characterization evaluation and in vitro antioxidant testing of Psidium guajava Stem. The results showed percentage yield of methanolic extract of Psidium guajava as 13.6%. The results of the phytochemical test indicated the presence of phenols, Diterpenes, proteins and amino acids, flavonoids, and carbohydrates. The TLC Profile results indicated the presence of flavonoids, a bioactive molecule with a variety of pharmacological actions. The DPPH method for determining antioxidant potential was performed. The IC50 value obtained for methanolic extract of Psidium guajava was 65.31%. From above obtained results it can be concluded that the stem of Psidium guajava have potent antioxidant potential. Keywords: Psidium guajava, Anti-oxidant, TLC, IC50