The effects of adding calcium hydroxide (Ca(OH)(2)) to a copper-CF (30 %) composite (Cu-CF(30 %)) were studied. After sintering at 700 A degrees C, precipitates of calcium oxide (CaO) were included in the copper matrix. When less than 10 % of Ca(OH)(2) was added, the thermal conductivity was similar to or higher than the reference composite Cu-CF(30 %). A thermal conductivity of 322 W m(-1) K-1 was measured for the Cu-Ca(OH)(2)(3 %)-CF(30 %) composite. The effects of heat treatment (400, 600, and 1000 A degrees C during 24 h) on the composite Cu-Ca(OH)(2)(3 %)-CF(30 %) were studied. At the lower annealing temperature, CaO inside the matrix migrated to the interface of the copper matrix and the CF. At 1000 A degrees C, the formation of the interphase calcium carbide (CaC2) at the interface of the copper and CFs was highlighted by TEM observations. Carbide formation at the interface led to a decrease in both thermal conductivity (around 270 W m(-1) K-1) and the coefficient of thermal expansion (CTE (10.1 x 10(-6) K-1)).