The inhibition efficiency of 3,4-diaminobenzonitrile was studied against steel corrosion, using electrochemical impedance spectroscopy, potentiodynamic measurements and solution assay analysis. The corrosion rate was determined with different routes; apparent Stern-Geary coefficient (B) derived from solution assay analysis and compared with coefficient value obtained from Tafel slopes. For blank solution, B and corrosion current values were quite different, comparing results from Tafel slopes and AAS. In presence of inhibitor, the difference becomes negligible. Once anodic dissolution kinetics is governed by strongly adsorbed inhibitor, resistance against charge transfer process becomes more important and corrosion rate results obtained from different routes come closer. (C) 2015 Elsevier Ltd. All rights reserved.