Ion scattering techniques in the 5–50 keV range have the potential to yield quantitative information on the composition of high‐temperature superconductor (HTc) films. To demonstrate this we have designed and built an ion scattering spectrometer, compact enough forinsituuse, as an analytical tool for vacuum deposition processes. Data collected from La2−xSrxCuO4films demonstrate the excellent mass resolution available using heavy incident ions. Modeling of the data has been carried out using both a simple empirical method and a full Monte Carlo code. In addition to stoichiometric information, the contribution of light recoiled elements to the spectrum is determined. The estimated composition, based on these models is compared with the composition obtained using high energy Rutherford backscattering spectrometry (RBS) to verify the quantitative capabilities of the technique. ©1996 American Institute of Physics.