rutherford backscattering spectrometry (rbs) has been applied to films of the high-temperature superconductor yba/sub 2/cu/sub 3/o/sub 7/. the films were prepared by rf and dc sputtering and silk-screen printing onto substrates of alumina, sapphire and magnesia. some of the samples were exposed to various heat treatments in order to promote the superconducting phase. a 2 mev beam of he/sup +/ particles from the 3 mv dynamitron accelerator at birmingham university's school of physics and space research was employed for the rbs measurements. the composition and the depth profile of the elements in the films were determined by simulating the observed rbs spectra with a simulation software package. the simulations show that the heat treatment causes marked interdiffusion of the film and substrate. the experimental results and the computer simulations shown in this paper illustrate the advantages of using rbs to characterise films of the new superconducting materials