The inhibition activities of 2-hydroxy-5-methylacetophenone thiosemicarbazone (1), (Z)-2-(((E)-1-(2-hydroxy-5-methylphenyl)ethylidene)hydrazono)thiazolidin-4-one (2), (E)-3-(2hydroxy-5-((E)-phenyldiazenyl)phenyl)-1-phenylprop-2-en-1-one (3), (E)-1-(4-bromophenyl)-3-(2-hydroxy-5-((E)-phenyldiazenyl)phenyl)prop-2-en-1-one (4), (E)-5-(2-hydroxy-5-(phenyldiazenyl)phenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide (5), (E)-3-(4-bromophenyl)-5-(2-hydroxy-5-(phenyldiazenyl)phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide (6), 2,2'-((1E,1'E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(4-((E)phenyldiazenyl)phenol (7) and 2-((Z)-2-hydroxy-5-((E)-phenyldiazenyl)benzylidene)hydrazine-1carbothioamide (8) were explored by means of weight loss measurements for mild St-3 specimen in brine-kerosene solution. The corrosion rates of the St-3 drops as the inhibitor concentration increases together with increase of inhibition efficiencies. Thermodynamic parameters of adsorption on the St-3 surface at different concentrations were calculated.