The indentation creep of free-standing Y-ZrO2 layer and 20Sc-60Si-20Mg-80O-20N oxynitride glass has been investigated. Creep experiment has been performed with flat cylindrical indenter (hot pressed SiC) in the temperature range from 860 °C to 1300 °C at the loads from 20 to 100 MPa. The strain-time relationship was registered and the creep exponent and activation energy of creep have been calculated. The microstructure changes have been observed and documented. Viscosity as a function of temperature and the glass transition temperature (Tg) were determined in oxynitride glass and compared with values from compressive creep.