MgO/Cu composites reinforced with 1.0 vol.%, 1.5 vol.%, 2.0 vol.%, 2.5 vol.% and 3.0 vol.% MgO particles were fabricated by powder metallurgy. The effect of MgO particles on the thermal expansion behavior of MgO/Cu composites was studied, and the thermal expansion properties of MgO/Cu composites prepared were evaluated by the coefficient of thermal expansion at the temperatures range from 50 degrees C to 500 degrees C. The results show that the introduction of MgO particles significantly reduces the coefficient of thermal expansion of copper matrix. The increased temperature enhances the coefficient of thermal expansion of MgO/Cu composite, whereas more MgO content decreases the coefficient of thermal expansion of MgO/Cu composite. The thermal expansion properties of MgO/Cu composites were calculated by theoretical models. The calculated pressure values at the interface between MgO particles and copper matrix suggest that plastic deformation can occur at 350 degrees C, which is consistent with the variations of the measured coefficient of thermal expansion. (c) 2012 Elsevier Ltd. All rights reserved.