6-Nitro-7-(4'-nitrophenyl)-5-ethyl-4,7-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate (1) is one of promising antitumor compounds exhibiting biological activity against type 2 casein kinase, which is currently considered as a promising target in chemotherapy. Using the method of cyclic voltammetry, it was shown that the electrochemical activity of compound 1 in a mixed solution of Tris-HCl and ethanol (1 : 1) at pH 7.5 on a glassy-carbon electrode is due to the electrochemical reduction of the nitro group conjugated with the phenyl ring. A method was developed for the determination of compound 1 by direct cathodic square-wave voltammetry. The linearity region of the corresponding calibration curve obtained in a solution of a mixture of Tris-HCl and ethanol (1 : 1) at pH 7.5 is 5–500 mg/L (R2 = 0.988), the limit of detection is 0.8 mg/L, the limit of quantification is 2.4 mg/L. The accuracy of the developed procedure is close to 100%, the relative standard deviation is 1.4%.