This in vitro investigation characterized temperature changes associated with radiofrequency (RF) energy induced heating of bovine capsular tissue using newly developed, temperature-controlled monopolar (Vulcan RF system and Vulcan, TAC-S Electrothermal Probe) and bipolar (VAPR II RF system and VAPR TC RF electrode) RF systems and electrodes. Bovine capsular tissue samples were placed in a saline bath maintained at room temperature. Both RF generators were used at settings of 75 degrees C and 40 W. The RF electrodes were placed in stationary positions on the tissue samples and activated for 1- to 10-s. A fluoroptic thermometry system was utilized to record temperatures at the RF electrode-tissue interface at 1-s intervals. The results indicated that the mean tissue temperatures for the monopolar RF electrode tended to be higher than those produced by the bipolar RF electrode, especially during the 2- to 10-s RF delivery time intervals (P<0.05). Notably, during the 2- to 10-s time intervals the monopolar RF electrode produced mean tissue temperatures that exceeded the set temperature of 75 degrees C (range of differences +1.2 to +15.7 degrees C highest mean temperature 90.7 degrees C). By comparison, the bipolar RF electrode maintained tissue temperatures relatively close to the set temperature(range of differences -3.2 to +2.7 degrees C; highest mean temperature 77.7 degrees C). These findings provide basic temperature profiles for the two new temperature-controlled RF devices.