The aminophenyl (AP) functionalized AuNPs (AP-AuNPs) were synthesized in aqueous medium by spontaneous grafting method and were used for the formation of AuNPs film on glassy carbon (GC) and indium tin oxide (ITO) surfaces by potentiodynamic method. The formed AP-AuNPs film modified electrodes were characterized by cyclic voltammetry (CV), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). EIS studies show that the electron transfer reaction of [Fe(CN)(6)](3-/4-) was higher at the AP-AuNPs film modified electrode (1.58 x 10(-4) cm s(-1)) than at bare (3.78 x 10(-5) cm s(-1)) GC electrode. The surface coverage of the AP-AuNPs film modified electrode was found to be 4.4 x 10(-10) mol cm(-2). The film formation takes place via -NH2 groups of AP-AuNPs, which was confirmed by XPS from the observed peaks corresponding to =N-H (396.7 eV), -N-H (399.2 eV), -N = N- (400.2 eV) and -N+-H (403.3 eV). The AP-AuNPs film modified electrode was successfully utilized for the determination of histamine H-2 receptor antagonist ranitidine (RA). Further, the AP-AuNPs film modified electrode was effectively used for the selective determination of RA in the presence of 40-fold excess paracetamol. The present method was successfully used to determine the concentration of RA in commercial drugs. (c) 2013 Elsevier Ltd. All rights reserved.