We describe a novel technique for measuring electrochemical impedance, in which the electrode potential is ramped to a desired bias potential and a small potential step is applied to the working electrode after a short time delay. Fourier transform of the first derivative of the current signal thus obtained provides ac currents in the frequency domain, which allows the computation of impedances of the electrode/electrolyte interface in the whole frequency range. A home-built data acquisition system for these measurements and the results obtained therefrom were used for the measurements. The advantage of the technique includes an extremely short time of less than 1 ms for impedance measurements in the whole frequency region while equilibrium conditions of the electrochemical system are being maintained before and after the measurements, among many others. This technique is expected to revolutionize electrochemical measurements and to find important applications such as in situ measurements during battery cycling, corrosion testing, and other electrochemical experiments.