The inhibition effect of 4-[(E)-(phenylimino)methyl]phenol (PIP), 4-[(E)-(4-fluorophenylimino)methyl]phenol (FIP). 4-[(E)-(4-chlorophenylimino)methyl]phenol (CIP), 4-[(E)-(4-bromophenylimino)methyl]phenol(BIP) and 4-[(E)-(4-nitro-phenylimino) methyl]phenol (NIP) oil file conosion of mild steel in hydrochloric acid was investigated. The corrosion inhibiting action was studied through weight loss and electrochemical techniques. The corrosion p parameters such as anodic and cathodic Tafel slopes (b(a) and b(c)), corrosion potential (E-corr), corrosion current densities (I-corr), surface coverage (theta) and corrosion inhibition efficiencies %IE were determined. The polarization measurements indicated that the inhibitors are of mixed type. The adsorption obeyed Langmuir adsorption isotherm. The inhibition efficiencies increased with increase ill inhibitor concentration but decreased with increase in temperature and also with increase in acid concentration. The activation and thermodynamic parameters were calculated for different temperatures.