Abstract An improvement of the the Trolox® equivalent antioxidant capacity (TEAC) assay, using the ABTS+. radical-cation discoloration method, produced a highly efficient method for the exploration of the natural and/or synthetic product antioxidant capacity (AOC). The improved method was developed in a Versamax 96-well microplate reader with data acquisition software, SoftMax® Pro-software. The proposed method incorporated three modifications: areaction-time increase to near completion; an assay miniaturization using 96-well multiplate reader, and TEAC value determination of the relationship between the 50 % inhibitory concentrations (IC50) of the tested substances and Trolox®, under equilibrium. The modifications led to a substantial decrease of: 1. 1. assay sample amounts (from 10–500 mg to 0.08–20 mg, range of reading);2. 2. solvent volumes (from 1–3 mL to 200 μL, per sample in each reading);3. 3. reading error (blank for each used plate-column) (% RSD <_ 5 %); and,4. 4. TEAC value underestimation for the tested molecules (close-to-equilibrium conditions at 30 min). This methodology provides efficient and fast processing of a great number of samples (3 samples with 12 dilutions, by duplicate, with their blanks, in 30 min) as well as friendly data management.