The influence of hydrazone derivatives on the corrosion of nickel in 2 mol L-1 hydrochloric acid solution has been studied using weight loss and galvanostatic polarization techniques. In general, at constant acid concentration, the inhibition efficiency increases with increasing the inhibitor concentration and decreases with increasing temperature. Polarization studies indicate that the compounds act as mixed- type inhibitors. The addition of iodide ions enhances the inhibition efficiency to a considerable extent .The effect of temperature on corrosion inhibition has been studied and activation energy has been calculated. Some thermodynamic parameters are calculated and discussed.