Three organic inhibitors namely, 5-mercapto-3-butyl-4-salicylidineimino-1,2,4-triazole (MBST), 5-mercapto-3-butyl-4-. benzylidineimino-1,2,4-triazole (MBBT) and 5-mercapto-3-butyl-4-cinnamylidineimino-1,2,4-triazole (MBCT) were synthesized in the laboratory and their influence on the inhibition of corrosion of mild steel (MS) in. aqueous solutions containing IN HCl and IN H2SO4 was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency (IE) of these compounds was found to vary with concentration, temperature and immersion time. Good inhibition efficiency (IE) was evidenced in both acid solutions. The adsorption of these compounds on the steel surface for both acids was found to obey Temkin's adsorption isotherm. The potentiodynamic polarization data have shown, that, compounds studied are mixed type inhibitors in both the acid solutions.