A digital AC voltammetric technique in which the perturbation signal is obtained from a computer-controlled analog function generator is described. This approach overcomes the limitation of the upper frequency inherent in computer generated sinusoidal signals. The measurement of the current at a constant phase angle of the input sine wave is facilitated by synchronizing the current digitization with the triggering of the function generator. The frequency of the sine wave is controlled by the computer, through the voltage-controlled-oscillator of the function generator. A program based on the Fast Fourier Transform (FFT) algorithm is used to extract the frequency information from the total cell current and to discriminate against charging current. All the components used in the instrumental design are commercially available.