Diamondlike carbon films were deposited on silicon, gallium arsenide and aluminum substrates using ion-assisted chemical vapor deposition. The stress of these films was measured as a function of temperature between 25 and 150-degrees-C. Using the stress-temperature measurements, the average linear thermal expansion coefficient was found to be 2.3 ppm/degrees-C, while the biaxial elastic modulus 1.74 X 10(11) Pa.