The push-rod dilatometer is the most widely used and popular commercial apparatus for measuring the thermal expansion coefficient of metals, it should be metrological verified before testing. Certified reference materials are the most applicable and effective means of verifying such equipment. Here, a reference material [termed Pyros (Ni-based) alloy] was developed for measuring the thermal expansion coefficient. The Pyros alloy reference material exhibited a high thermal expansion coefficient: a range of 12.7–16.8 (× 10–6 °C−1). The maximum temperature of the certified value was 1000 °C. This range and value almost span the entire application needs of metals, especially steel alloy or superalloys. Thus, Pyros alloy is suitable as a reference material for validating the push-rod dilatometer based on comparative measurements.