Astringency, an important characteristic of red wine quality, is caused by the interaction of salivary proteins with condensed tannins present in grapes. The development of measurement methods for tannins is an important area in wine quality research. Electrochemical methods have previously been reported in correlating astringency with measurement response, but additional information regarding the physicochemical characteristics of individual tannins is needed to improve these methods. In this research, flavan-3-ol monomers, dimers and trimers, from locally grown tempranillo grapes, have been isolated using high-performance liquid chromatography (HPLC). Chromatograms of these grape samples indicate significant amounts of tannin monomers and dimers. The electrochemical response of these isolated tannins will be used to determine the diffusion coefficient of each molecule in a model wine matrix. This research serves as a first step toward understanding the relationship between the electrochemical characteristics of flavan-3-ols and their contribution to astringency in red wines.