1.The transformation conditions (different cooling conditions) of the solid solution in the austenitic precipitation-hardening alloy KhN35VT strongly affect the strength and plastic characteristics in short-term and long-term tension. 2.Isothermal treatment with single-stage tempering increases the long-term plasticity 150\2-300% by comparison with the standard treatment and also increases the creep resistance and long-term strength, which is most notable at low stresses. In comparison with the same tempering after the standard treatment, two-stage tempering increases the plasticity and creep resistance by 200–300 and 200–500% respectively, while the long-term strenght remains at the same level or increases slightly. 3.After isothermal treatment with a low first tempering temperature (650\dgC) the impact strength after soaking at 650\dgC for 3500 h drops to approximately half its original value. With a high first tempering temperature (800\dgC) the impact strength decreases to a lesser extent-no lower than 6 kgm/cm2. 4.It was confirmed that in double tempering of austenitic steels the first tempering temperature has a notable effect on the properties. The stability of the properties at working temperature depends on the proper conditions of the first tempering.