The technique developed by Jamieson and Lawson for x‐ray diffraction at high pressure has been modified so that low‐Z materials can be studied under high pressure conditions to 12 GPa. A beryllium annulus replaces the commonly used boron annulus, allowing the use of Cu K&agr;or Fe K&agr;radiation, thus improving the accuracy ofd‐space determinations. The inclusion of a 4:1 methanol‐chanol mixture developed by Piermarini,et al.relieves pressure gradients and anisotropy, improving both the quality and range of compression data. Excellent compression results are obtained in the 0–1 GPa region where x‐ray techniques have formerly been inaccurate.