A new design of X-ray camera for use with specimens at temperatures up to 1000° C is described. The specimen under examination, in fibre form, is situated at the centre of an electric furnace which is so mounted that it can be removed without disturbing the specimen, and the whole is enclosed in a chamber which can be evacuated. The camera is mounted outside this chamber and can be removed for processing the photographic film, and replaced again in position, without disturbing the rest of the apparatus. The specimen is made to rotate in vacuo by a magnetic device. Temperatures are measured with a platinum/rhodio-platinum couple. Samples of the structure-spectra of pure iron, taken when the material was maintained at 800° C and 950° C in vacuo, are given.