To date, most applications of materials having very low thermal expansion have been near 20°C. In 1968 Plummer and Hagy reported measurements on some low‐expansion materials using Fizeau interferometry attaining high precision and accuracy. These measurements were limited to a maximum temperature of 80°C. In response to interest in expansion of these materials at somewhat higher temperatures, the apparatus has been modified to permit measurements to 130°C. Results of these measurements are reported.