The corrosion inhibition efficiency of two Schiff bases 4-salicylideneatnino-3-methyl-1,2,4-triazole-5-thione (SAMTT) and 4-(2,4-dihydroxybenzylideneamino)-3-methyl-1H-1,2,4-triazole-5(4H)-thione (DBAMTT) on mild steel in hydrochloric acid was tested by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results revealed that both SAMTT and DBAMTT act as excellent inhibitors, and the inhibition efficiencies obtained from the weight loss and electrochemical experiments were in good agreement. Scanning electron microscopic and atomic force microscopic images showed the efficiency of the compounds as inhibitors on mild steel in acid media, and both surface analysis techniques revealed that the inhibition occurs due to adsorption of the inhibitor molecules at the metal/solution interface.