This paper reports the electroanalytical determination of condensed tannins in extracts of Acacia (Acaciamearnsii de wild) using a glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs) andcarboxymethylcellulose (CMC). The AuNPs were synthesized by the reduction of chloroauric acid withsodium borohydride using CMC as a stabilizer. The characterization of the AuNPs was carried out byUV–vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). Themodified surface was characterized by scanning electron microscopy with field emission gun (SEM-FEG),atomic force microscopy (AFM) and profilometry experiments. Electrochemical studies were carried outby electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square-wave voltamme-try (SWV). The results show that the nanoparticles obtained are spherical and have an average diameterof 5.3 nm. The modified electrode was prepared by dropping the AuNPs-CMC dispersion onto the sur-face of the GCE. For the quantification of condensed tannins catechin was used as a model compound.The detection (DL) and quantification (QL) limits for catechin were 0.274 and 0.831 mol L−1, respec-tively. The proposed detector was tested by determining the total condensed tannins concentration inreal samples using the standard addition method. The curves for the samples exhibited a slope similar tothe calibration curve, indicating the absence of interference from the matrix components in the responseto condensed tannins. The modified electrode was successfully applied to the analysis of real samples,with results comparable to those obtained using the Folin-Ciocalteu method. Thus, the strategy used inthis study creates new opportunities for the sensitive detection of condensed tannins in plant extractswidely used in various industrial segments