The effect of 1-(3-phenoxypropyl) pyridazin-1-ium bromide, a new pyridazinium derivative, on steel corrosion in a HCl (1 M) solution was analyzed using electrochemical impedance and XPS spectroscopy. Experimental results indicated that the inhibition efficiency increased with an increase in an inhibitor concentration. Electrochemical impedance spectroscopy measurements revealed that an increase in the immersion time of steel in an acidic medium from 1 to 12 h and further to 24 h decreased the charge transfer resistance (R-ct) and thus decreased the inhibition efficiency. The SEM and XPS analyses linked the inhibition effect to the adsorption of the inhibitor (1-(3-phenoxypropyl) pyridazin-1-ium bromide) on the steel surface. (C) 2019 Elsevier Inc. All rights reserved.