The use of natural products as therapeutic agents goes back to the first civilizations. A large percentage of the drugs prescribed worldwide come from plants, as compounds can be used unaltered or applied to the semi-synthesis of more potent ones. Phenolic compounds are secondary plant metabolites widely distributed in nature. They are known for their several health promoting properties, such as vasoprotective, anti-inflammatory, antimicrobial and antioxidant. Their antioxidant capacity has been the object of intensive research towards their application in cancer, cardiovascular and neurodegenerative diseases, as well as in antiaging cosmetic products. In this review we present the recent advances in the methodology used for the extraction, purification and analysis (separation, detection and structural elucidation) of these compounds, from species largely consumed and with ethno-pharmaceutical relevance, as they are applied in the quality/ authenticity control of vegetal matrices. The biochemical assays usually employed to assess their antioxidative potential will also be included. These comprise those testing their ability to scavenge both reactive oxygen and reactive nitrogen species and those evaluating their capacity to prevent the formation of these species.