The adsorption and inhibition efficiency effect of enaminonitrile derivatives on the Cu10Ni alloy in 0.5 M HCl were investigated using electrochemical techniques (potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM)). The inhibition efficiency of the inhibitors increased with increasing the concentration of the derivatives and decreased with increasing the temperature. Polarization curves revealed that these compounds are mixed type inhibitors. The adsorption of these compounds follows Temkin adsorption isotherm. Some thermodynamic parameters of activation and adsorption processes were also determined and discussed.