This work presents theoretical and experimental studies on a passively actuated bi-metallic heat switch for space applications. The working principle of the heat switch is based on the differential thermal expansion of distinct metals. Analytical one-dimensional and two-dimensional heat conduction models are developed to predict the thermal resistance of the heat switch, which is a function of temperature. A non-dimensional parametric analysis is performed in order to study how the design parameters affect the total thermal resistance of the heat switch. The theoretical models are also compared with experimental data obtained from a prototype of the heat switch. The agreement between theory and experiments is good. (C) 2003 Elsevier Ltd. All rights reserved.