Thermal interface pastes based on silicone, lithium doped polyethylene glycol (PEG), and sodium silicate were evaluated in their performance before and after heating up to 120°C. The thermal contact conductance of any of the pastes between copper disks decreased after heating, such that the fractional decrease was less for the silicone-based paste than the PEG-based and sodium-silicate-based pastes. Nevertheless, the conductance was lower for the silicone-based paste than the other pastes both before and after heating up to 100 cycles.