Indole was tested as a corrosion inhibitor for stainless steel (316 L) in acidic and alkaline solutions (0.3 M NaCl, pH = 4, 8 and 10). For this aim, current-potential curves and impedance measurements were used. All the experimental results showed that indole could provide an effective protection for stainless steel in chloride solution at pH = 4. The inhibiting effect of indole is proposed to be on the anodic process rather than cathodic branch. On the other hand, indole was found to have no significant efficiency on the corrosion of the metal in alkaline solutions. (C) 2004 Elsevier B.V. All rights reserved.