The investigation of the inhibition of the corrosion of steel in 0.5M HCl and H2SO4 was carried out by using electrochemical impedance spectroscopy (EIS) technique, potentiodynamic polarization measurements and spectrophotometric analysis. The thesis consists of three chapters. Chapter I is the introduction, Chapter II represents the experimental techniques, and Chapter III contains the results and their discussion. In the first chapter an introduction was given which deals with the corrosion and its inhibition, literature survey of the inhibition of steel corrosion in acid solutions using plant leaf extract and the aim of the work. Chapter two showed the experimental techniques used in the investigation. The third chapter showed the obtained results and their discussion in eight parts. • Part 1 represents effect of plant leaf extracts, Ziziphus, Diospyros kaki, and Myrtus Communis L leaf extracts, on the corrosion inhibition of steel in 2M HCl. • In part 2 shows effect of plant leaf extracts, Ziziphus, Diospyros kaki, and Myrtus Communis L leaf extracts, on the corrosion inhibition of steel in 0.5M H2SO4. • Part 3 clarifies comparative Studies for electrochemical techniques, effect of acid anions. • Part 4 represents effect of temperature on the corrosion inhibition of steel in the absence and presence of plant leaf extracts in 2M HCl and 0.5M H2SO4. • Part 5 shows their adsorption isotherms • Part 6 represents spectrophotometric analysis for plant leaf extract • Part 7 indicates the structures of the chemical Constituents of plant leaf extracts. • Part 8 shows the effect of Linalool and caffeine on the corrosion of steel in 2M HCl and 0.5M H2SO4, effect of temperature, adsorption Isotherms. • Part 9 represents comparative and visibility Study