The effect of a schiff base 2-(2-hydroxybenzylideneamino)phenol (HBAP) and its corresponding three 3d-transition metal complexes viz. Mn-HBAP, Co-HBAP and Ni-HBAP on the corrosion inhibiting behaviour against chrome steel bearing balls in 0.1 N HNO 3 solution were investigated by means of conventional weight loss method, potentiodynamic polarization and scanning electron microscopy (SEM) studies. The adsorption nature of all inhibitors over chrome steel surface were spontaneous and were best

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... ted by Langmuir's adsorption isotherm. Stability of complexes in acid media were supported from spectrophotometry measurements. The mixed mode of inhibition was confirmed from polarization and inhibition efficiency (% I.E.) could be increased with concomitant increase in inhibitor concentration in bulk experimental solution. Correlation between the inhibitive effect and molecular structure of inhibitor's was further supported by Density Functional Theory (DFT) like quantum chemical calculation. An effective quick prediction about each and individual inhibitor on inhibitor/metal interface about simultaneous effect of varying concentration and reaction time was successfully exploited by Design of experiments (DOE).