Adherent, highly reflective films of Ru and Os have been deposited in vacuum on heated Si substrates by thermal decomposition of the pentacarbonyls Ru(CO)5 and Os(CO)5, at 150 and 200 °C, respectively. Auger analysis after ion bombardment cleaning revealed nearly O-free surfaces, with slight C contamination which grew with exposure to the primary electron beam, thus making accurate determination of C content difficult. X-ray diffraction showed the films to be polycrystalline with the expected hexagonal close-packed structure, while measured resistivities were about a factor of 3 greater than bulk values. This method of depositing Ru and Os offers the advantages of simplicity, modest temperature requirement, and metallization of heated surfaces only.