A novel electrochemical sensor based on (3-aminopropyl)triethoxysilane (APTES) functionalized SiO2 supported Au nanoparticles and Nafion (Nf) as the protective membrane was fabricated for the electrochemical determination of H2O2 in contact lens-cleaning solution. The modification steps of glassy carbon working electrode (GCE) were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The amperometric results showed that Nf/Au@SiO2-APTES/GCE sensor can be used to determine H2O2 in contact lens solutions with the linear ranges of 14-180 mu M and 0.18-7.15 mM, excellent sensitivities of 2514.6 and 894.2 mu A mM cm(-2), and a low limit of detection (LOD) of 4.25 mu M depending upon signal-to-noise ratio of 3. Nf/Au@SiO2-APTES/GCE exhibited excellent repeatability with relative standard deviation (RDS) of 2.66% and acceptable reproducibility with RSD of 3.35%. The sensor displayed reasonable selectivity in the presence of uric acid, dopamine, ascorbic acid, glucose, mannose, glycine, fructose, histidine, and arginine with RSD less than 2.5%. The fabricated Nf/Au@SiO2-APTES/GCE sensor has been successfully applied to detect H2O2 in contact lens cleaning solutions.