EIS measurements of ITO microchip were performed in 50 mM [Fe(CN)6] 3-/4-+ 0.1 M KCl solution. Impedance spectra were recorded at open circuit potential with a 10 mV amplitude signal in the frequency range of 10 Hz to 10 kHz . Rct values were calculated with fit and simulation option in AUTOLAB 302 Nova 2.1.5 software using Randles circuit model.