A novel water-soluble self-doped oligoaniline derivative (WSOAD) was synthesized by oxidative coupling method. The prepared WSOAD showed expected spectroscopic properties, and also revealed good solubility in strong polar solvents and aqueous media across a pH range of 1-14. WSOAD displayed excellent electroactivity in acid, neutral and even in alkaline solutions (pH = 10) due to self-doping effect between oligoaniline and sulfonic acid groups. Moreover, the inhibition effect of WSOAD on the cold rolled steel in 1.0 M HCl solution was studied by weight loss and potentiodynamic polarization measurements. The results showed that WSOAD was a good inhibitor in HCl medium.(C) 2013 Elsevier Ltd. All rights reserved.