As one of the most promising alternative refrigerants, 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFE-356 mmz) is considered to have the potential to be applied in a high temperature heat pump and the organic Rankine cycle. The gaseous pvT properties of HFE-356 mmz were measured using the isochoric method in the temperature range from 333.068 K to 451.226 K, the pressure range from 104.9 to 1997.3 kPa, and the density range from 75.0 mol•m −3 to 882.0 mol•m −3 . The threeterm truncated virial equation of state for gaseous HFE-356 mmz was also fitted based on the experimental data.