Flupenthixol hydrochloride (FLP) has an antipsychotic activity against depression and is irTeversible oxidizable at the glassy carbon electrode in various buffer systems and at different pH values. The mechanism of the oxidation process was discussed. According to the linear relation between the peak current and FLP concentration, differential pulse and square wave voltammetric methods for its determination in pharmaceutical dosage forms and spiked human serum samples were developed. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in Britton-Robinson buffer at pH 7.02 (20% methanol) at 0.75 and 0.79V for differential pulse and square wave voltammetric techniques, respectively. The linear response was obtained in the ranges of 8 X 10(-7) to 1 X 10(-4)M with a detection limit of 1.17 x 10(-7) M for differential pulse and 1 X 10(-6) to 1 X 10(-4) M with a detection limit of 2.86 x 10(-7) M for square wave voltammetric techniques. The repeatability and reproducibility of the methods for both media (supporting electrolyte and serum sample) were determined. Precision and accuracy of the developed method were used for the recovery studies. The standard addition method was used for the recovery studies. No electroactive interferences were found in biological fluids from the endogenous substances and additives present in tablets.