Bioaffinity sensors need to be rapid, specific, and highly sensitive. To realize these features, electrodes that can elicit high electrochemical performance are necessary. In this study, we developed nanorod array electrode and performed cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments to study the interfacial properties of the nanorod array electrode with Fe(CN)(6)(3-/4-) as the redox molecules. Results showed that both the CV and EIS measurements captured very well the resistive and capacitive changes due to the adsorption of functionalizing molecules and the coupling between avidin and biotin. The EIS measurements were more sensitive in discriminating small changes caused by the surface adsorption of various molecules. The use of avidin-functionalized gold nanorod modified electrodes had led to much increased detection sensitivity along with a detection-limit as low as 1 ng/mL of biotin.