This part of IEC 61788 describes measurements of the intrinsic surface impedance (ZS) of HTS films at microwave frequencies by a modified two-resonance mode dielectric resonatormethod [13, 14]2. The object of measurement is to obtain the temperature dependence of the intrinsic ZS at the resonant frequenc y f0. The frequency and thickness range and the measurement resolution for the intrinsic ZS of HTS films are as follows: f requency: up to 40 GHz; f ilm thickness: greater than 50 nm ; m easurement resolution: 0 ,01 mΩ at 10 GHz. The intrinsic ZS data at the measured frequency, and that scaled to 10 GHz, assuming the f2 rule for the intrinsic surface resistance RS (f < 40 GHz) and the f rule for the intrinsic surface reactance XS for comparison, shall be reported.