A high temperature precision x‐ray camera has been designed and constructed by modification of the familiar back‐reflection symmetrical focusing type of camera. The camera, specimen, and furnace are used within a vacuum chamber to avoid oxidation. The apparatus in its present form has been employed at temperatures up to 1000°C, but higher temperatures could be easily attained by making a few minor changes in the furnace materials.The lattice parameters of beryllium have been measured up to 1000°C. The derived coefficients of thermal expansion, both linear and bulk, are presented as a function of temperature. In addition, the data present strong evidence that the hexagonal close packed form of beryllium which exists at room temperature is stable up to at least 1000°C, contrary to several reports in the literature.