Rates of mass transfer at a rotating cylinder of the hexagonal cross section were measured by the limiting current method. A drag-reducing polymer diminished the speed of mass transfer depending on polymer quantity and rotation speediness. Rotating hexagonal cylinders provided higher degrees of mass transfer than circular rotating cylinders under identical conditions. The performance of rotating hexagonal cylinders in eliminating Cu2+ from dilute liquids was examined and found to be satisfactory. Besides the diffusion-controlled electrochemical reactions like anodic oxidation of organic contaminants, the reactor can remove organic pollutants via catalytic diffusion-controlled reactions. The high degree of heat transfer from the cylinder to the liquid would prevent possible hot spots, catalyst deactivation, and decomposition of products.