The rates of infusion of theaflavins, thearubigins, and caffeine from Koonsong Broken Pekoe into water were measured at 79.5 and 94.0°C. The kinetic data have been interpreted in terms of a simple two-phase model, and the rate constants of infusion and of re-absorption were calculated. At low infusion times thearubigins were extracted faster than theaflavins, with the caffeine rate intermediate. However, the rate constants for the overall infusion process were quite similar for the three constituents. The corresponding activation energies are small as are those calculated from Long's data on the rate of extraction of all soluble material.