A new technique for determining the concentration of gases in films has been developed which utilizes laser-induced flash evaporation followed by mass-spectrometric analysis of the released gas. It is shown that this technique can be used to perform quantitative analysis for the noble gases and nitrogen in most thin-film materials on a wide variety of substrates. Under ideal conditions, gas concentrations of a few parts per billion can be detected. Qualitative results have been obtained for other chemically active gases such as oxygen and hydrogen. Approaches are suggested which may also allow quantitative measurements to be made for these gases. Several phenomena which could lead to inaccurate or erroneous measurements are evaluated and methods suggested for minimizing their effect. © 1972 The American Institute of Physics.