Abstract This paper describes a simple and rapid photocatalytic pretreatment procedure that removes contaminants from glassy carbon (GC) surfaces. The effectiveness of TiO2 mediated photocatalytic pretreatment procedure was compared to commonly used alumina polishing procedure. Cyclic voltammetric and chronocoulometric measurements were carried out to assess the changes in electrode reactivity by using four redox systems. Electrochemical measurements obtained on photocatalytically treated GC electrodes showed a more active surface relative to polished GC. In cyclic voltammograms of epinephrine, Fe(CN)63−/4− and ferrocene redox systems, higher oxidation and reduction currents were observed. The heterogeneous electron transfer rate constants (ko) were calculated for Fe(CN)63−/4− and ferrocene which were greater for photocatalytic pretreatment. Chronocoulometry was performed in order to find the amount of adsorbed methylene blue onto the electrode and was calculated as 0.34 pmol cm−2 for photocatalytically pretreated GC. The proposed photocatalytic GC electrode cleansing and activating pretreatment procedure was more effective than classical alumina polishing.