Glassy carbon electrode surface has been modified with catechol encapsulated in cetyltrimethylammonium bromide (CTAB) or sodium dodecylsulphate (SDS) surfactant film. The modified electrodes show quasi reversible cyclic voltammograms in tris buffer at pH 7.0 with redox potential values + 0.250 V and + 0.185 V respectively, using Ag-AgC1 (3M NaC1) as reference. Addition of thiourea into the electrolytic medium increases the cathodic and anodic currents of the modified electrodes. Anodic current of CTAB film modified electrode is increased by 18 times while cathodic current increased by 1.8 times. However, SDS film modified electrode shows an increase in anodic current by 5.5 times and that in cathodic current by 8.0 times at 3x10(-7) M concentration of thiourea compared to that at zero thiourea concentration in electrolytic medium.