Electrochemical behaviour of zopiclone was investigated on glassy carbon electrode in static and rotation disc arrangement. Strong influence of kinetics and adsorption phenomena on the electrode processes was proved by voltammetric techniques. Controlled potential electrolysis in off-line and on-line combination with tandem mass spectrometry was employed for investigation of the products of electrochemical oxidation. N-Desmethyl zopiclone was identified and three other oxidation products formed by an introduction of one or two oxygen atom(s) to the molecule of zopiclone (including zopiclone N-oxide) were characterized. Based on mass spectrometric investigation of those products, piperazine moiety was proved as a target of electrochemical oxidation of zopiclone. Since N-desmethyl zopiclone and zopiclone N-oxide have been reported as products of enzymatic metabolism of the drug, the combination of electrochemistry with mass spectrometry may be considered as a reliable tool for simulation of some metabolic transformations.