The effect of Citrus reticulata extracts on the corrosion of copper in 1M NaOH solution was studied using weight loss method at various temperatures varying from 298 to 328 K. Experimental data revealed that Citrus reticulata extract acted as an inhibitor in the alkaline environment. It was found that the inhibition efficiency increased with an increase in Citrus reticulata extract concentration. Adsorption enthalpies were determined and discussed. Effect of temperature was also investigated and activation parameters were evaluated.