The electrochemical behavior of clarithromycin (CAM) was studied in pH 1.8～9.2 Britton-Robinson buffer solution and 0.05 mol•L^－1 NaOH solution by means of linear sweep voltammetry, cy-clic voltammetry, normal pulse voltammetry and UV spectrophotometry. Over the studied pH range, four reduction waves P₁, P₂, P₃ and P₄ of CAM were achieved, three of which were the reduction of C＝O at C-9. CAM yielded one wave P₁ as pH of B-R buffer solution was changed from 1.8 to 5.7. P₁ was an irreversible and weak adsorption reduction wave involving two electrons. Additional two waves P₂ and P₃ were exhibited in pH 6.0～9.2 buffer solution. The former was an irreversible reduction wave involving two electrons, and the latter was a catalytic hydrogen wave. P₄ was attained in 0.05 mol•L^－1 NaOH solution, which was an irreversible and adsorption reduction wave in-volving one electron. Based on the linear relation between the peak current of P₄ and the concentration of CAM, a new method for determination of CAM was described.

Key words: voltammetry, reaction mechanism, clarithromycin