A wide range of chromatographic methods for the analysis of phenolic compounds in medicinal plants has been published over the years. However, no chromatographic methods with pulsed amperometric detection using a gold electrode have been described to analyze phenolic acids and flavonoids. Moreover, there is a lack of information regarding a modified mobile phase with β-cyclodextrin to determine these compounds in plants by RP-HPLC. For this reason, the present study developed and validated an HPLC-PAD method to determine 12 phenolic compounds in medicinal plants from Amazonia. The isocratic mobile phase was constituted by sodium phosphate 50 m mol L-1, methanol 30% (v/v), and β-cyclodextrin 1 m mol L-1 at pH 2.0. The method demonstrated low detection and quantification limits and robustness. The accuracy ranged from 82-114% for chlorogenic acid and rutin, respectively. Six species of medicinal plants from Amazonia used for medicinal and nutritional purposes were characterized and showed the presence of at least one of the phenolic compounds in the study.