The inhibition ability of N,N'-bis(4-formylphenol)-1,2-Diaminocyclohexane (4-HCD) on the carbon steel in 1 M hydrochloric acid solution was studied by electrochemical techniques and weight loss measurements. 4-HCD inhibited steel corrosion in I M HCI solution significantly and the inhibition efficiency increased with 4-HCD concentration. The results indicated that after 5 h, this inhibitor has a maximum percentage inhibition efficiency of approximately 71% in the presence of 2 mM inhibitor. The adsorption of the inhibitor was followed Langmuir adsorption isotherm with the standard adsorption free energy of -25.66 kJ mol(-1). Computational investigations of the studied inhibitor are performed by using HF method with 6-31++G(d,p) and 6-311++G(d,p) basis sets. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.