Two heterocyclic Schiff bases namely (E)-2-(1-(2-phenylhydrazono)ethyl)pyridine (or 2acetyl pyridine phenyl hydrazone) (2APPH) and (E)-2-(1-triazylidineethyl)pyridine (or 2acetyl pyridine semicarbazone) (2APSC) were synthesized, characterized and their corrosion inhibition behaviour as well as mechanism of inhibition were investigated by different techniques. Structural characterization includes NMR, Mass, IR and UV-visible spectroscopy and elemental analysis. Corrosion inhibition behaviour of aforesaid compounds on mild steel in 1M hydrochloric acid was examined by electrochemical methods including potentiodynamic polarization analysis and electrochemical impedance spectroscopic techniques. The mechanism of corrosion inhibition was explored and supplemented by adsorption and surface morphological studies. Quantum mechanical investigations on corrosion behaviour of compounds were also conducted and satisfying correlation was noticed between the results of corrosion measurement methods and quantum mechanical evaluations.