Effects of 1,5-naphthalenediol (ND) on corrosion inhibition of aluminum have been investigated in 0.50 M NaCl using potentiodynamic polarization, potentiostatic current-time, air-exposed potential, and electrochemical impedance spectroscopy measurements. The study was also complemented by the quartz crystal analysis (QCA), cyclic voltammetery, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Fourier transform infrared (FTIR) spectroscopy. The addition of ND to the electrolyte decreased both general and pitting corrosion of aluminum in 0.50 M NaCl to a great extent due to its adsorption on the aluminum electrode surface. The adsorption of ND passivated or blocked the flawed areas of the aluminum oxide film, and pits formed on the aluminum metal surface from the severe chloride attack. The SEM images showed that ND in 0.50 M NaCl precluded the pitting corrosion of aluminum at -600 mV vs. Ag/AgCl when applied for 150 min after a relatively long immersion time of seven days. The FTIR spectrum revealed that the ND molecules are adsorbed on the Al surface. The QCA data indicated that ND molecules are adsorbed rather strongly on the aluminum-covered QCA electrode. © 2005 The Electrochemical Society. All rights reserved.