An unconventional glancing-angle x-ray diffraction film technique is described in some detail. This technique, which enables analyses to be made of thin oxide films without removing them from their substrate material, is shown to be as sensitive as reflection electron diffraction, without the inaccuracies inherent in the latter technique. By way of illustration, the technique is applied to the analysis of the thin films formed on the surfaces of iron-chromium alloys when oxidized at temperatures less than 700°C. A special feature of this application is the analysis of the preferred orientation existing in the low-chromium-content alloys which had been oxidized at 650°C. Some tentative conclusions are made regarding the oxidational behaviour of these alloys at temperatures below 700°C.