We have used weight loss measurements, potentiodynamic polarization, and lectrochemical impedance
spectroscopy to study the inhibiting effect of N,N–di(polyoxyethylene)–4–dodecylaniline, with different
numbers of oxyethylene units, on corrosion of steel in a 1 M hydrochloric acid solution. We have
determined that the studied compounds are good corrosion inhibitors. The inhibition efficiency increases
with an increase in inhibitor concentration, an increase in the number of oxyethylene units in the chain
of the inhibitor, and a decrease in temperature. The inhibiting effect of the studied compounds is due to
blocking of the metal surface as a result of adsorption of the oxyethylene units of the inhibitor. The
adsorption process is described by the Freundlich isotherm. The indicated compounds act as mixed
(mostly anodic) corrosion inhibitors. We calculate some thermodynamic corrosion parameters.