Abstract: A set-up for the measurement of the frequency response of voltage measurement transformers under actual waveform conditions is presented. It is based on a two steps procedure that makes use of high voltage gas insulated capacitors and a digital bridge. It allows calibrations using distorted waveforms, with a fundamental tone at medium voltage level and superimposed harmonics up to 20% and 15 kHz. Some experimental tests are presented. Different frequency behaviors of voltage transformers are found with: different capacitive loading, different type of characterization (low voltage or medium voltage) different harmonic order.