Guettarda calyptrata A. Rich., originally from Cuba and known as “Contraguao”, has traditionally been used to counteract quickly and effectively burns produced by Comocladia dentate Jacq (Guao), vegetable species that secretes a highly caustic latex for skin and mucous membranes. A burn is a traumatic injury resulting in local and systemic injury with oxidative changes; in this sense the antioxidants play an important role. In order to offer aspects related to the quality and effectiveness of the plant, its pharmacognostic, phytochemical and antioxidant activity is presented. The morphoanatomical evaluation was carried out, physical-chemical parameters were determined for the crude drug and for the aqueous extract. The chemical profile of the extract was estimated by thin layer chromatography, ultraviolet-visible and quantification of total phenols by Folin-Ciocalteu and total flavonoids by the colorimetric method of aluminum trichloride (AlCl₃). Finally, the antioxidant activity was tested by the FRAP and DPPH techniques. Through the pharmacognostic study, the quality specifications of the drug and the extract were established. The methods of analysis used for the chemical profile suggested the presence of flavonoids and phenols in general. The aqueous extract showed antioxidant properties by the two methods evaluated. The study of G. calyptrata provided pharmacognostic, phytochemical and effectiveness as an antioxidant evidence, aspects to consider in the possible use of the plant by our Natural and Traditional Medicine.