Previous investigations into the use of interstitial inserts as a means of controlling the thermal conductance occurring across metallic contacts are reviewed. Vie factors influencing the choice of a suitable filler for a particular application are discussed. A mathematical model has been used to predict the behavior of a joint formed between the flat surfaces of two, originally isothermal, cylindrical components, one of duralumin and the other of a titanium alloy. Vie model was validated by comparing the predictions from it with experimental measurements. For this particular contact, aluminum cooking foil proved to be a superior insert to the more expensive, commercially advocated, thermal control materials for reducing contact resistances.