Potato dry matter was isolated from three cultivars of potato tubers at different times during growth. The physicochemical properties of these potato dry matters were characterized for starch and protein content, thermal properties by differential scanning calorimtery (DSC) and paste properties by rapid viscosity analysis (RVA). Dry matter content of potato tubers increased to the highest level and then decreased as growth processed. Superior cultivar potato had a lowest dry matter content and the highest protein content as compared to Snowden and Shepody potatoes. Gelatinization enthalpy and temperature of dry matter varied with growth times and potato cultivars. Immature potato tubers (the earliest harvest) resulted in the highest temperatures for gelatinization, pasting and retrogradation of dry matter, indicating the molecular structure of starch plays an important role in the functional properties of potato dry matter. The quality of table and processing potato could be affected by growth times and cultivars.