Fast Fourier transforms are introduced as a.unique digital data handling tool for square wave voltammetry. Theoretical square wave voltammogra.ms were examined to study the effect of experimental parameters in the spatial frequency domain. A new method was developed to determine truncation frequencies. A₀, the first spatial frequency, was shown to be an effective measure of peak height and its use in calibration curves was demonstrated. The real and imaginary spatial frequencies were shown to be sensitive measures of peak position. FFT square wave voltammetry was developed. The technique performs the current differencing scheme in the spatial frequency domain over spatial frequencies which are noise free. The technique was verified experimentally with solutions of lead (II) in HCl and thallium (I) in HNO₃. FFT linear parameter estimation analysis was introduced as a new digital data manipulation technique for fused peak analytical systems. The algorithm was tested theoretically and experimentally on various ratios of lead (II) to thallium (I) in nitric acid where the peak separation is approximately 70 millivolts. The algorithm performs the calculation over noise free spatial frequencies and significantly reduces the complexity of the calculation relative to the conventional case. / Ph. D.