Some new Schiff base nonionic surfactants were synthesized and characterized using FTIR and H-1 NMR spectroscopy. The corrosion inhibition effect of the synthesized surfactants on X-65 type tubing steel in deep oil wells formation water has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. Polarization data indicate that the selected surfactants act as mixed type (cathodic/anodic) inhibitors. EIS results show that the change in impedance parameters with the concentration of the surfactants studied is indicative of the adsorption of surfactant molecules on carbon steel surface. The adsorption of the inhibitors was well described by the Langmuir adsorption isotherm. Effect of temperature on the efficiency of the corrosion inhibition process was studied and the values of activation energy, enthalpy of activation and entropy of activation were calculated and discussed. The corrosion inhibition efficiency of the surfactants is correlated with surface tension measurements data. The protective film formed on the carbon steel surface was studied by scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDX) techniques. (c) 2010 Elsevier B.V. All rights reserved.