Abstract In this paper, we study the effect of substitution of three imidazoles: 1-vinyl-1H-imidazole (VyIm); 1- (2-Dodecylsulfanyl-ethyl)-1H-imidazole (DEEIm) and 2-Imidazol-1-yl-ethylsulfanyl)-acetic acid (ImESAA) on adsorption properties on the steel surface in molar HCl solution. The investigation was performed using weight loss data combined to theoretical parameters deduced from dynamic simulation. Various kind of Langmuir, Temkin, Frumkin, Freundlich, Flory-Huggins and El-Awady were investigated and discussed. The higher inhibition efficiency of DEEIm was explained by the length aliphatic chain leading to reinforce charge on sulfur atom and imidazole ring. Free enthalpy and other data deduced from isotherm kinds help to understand adsorption process. The DFT calculations were performed to estimate the chemical reactivity of the VyIm, ImESAA and DEEIm compounds at B3LYP/6-311++G(df,pd) level.