The aim of this work was to characterize the essential oils of Pistacia lentiscus (P.L) from Saidia Morocco and analysis by gas chromatograph interfaced with a mass spectrometer (GC-MS). The Corrosion inhibition effect of organic oil and extract of leaves of Pistacia lentiscus (P.L) of mild steel in 1M HCl solution was carried out using, gravimetric, electrochemical polarization and EIS methods. Experiments are performed by varying concentration of the inhibitor. The inhibition efficiency increases with increased organic oil and extract concentration to attain a maximum value of 96.34 % and 86.59% at 1g/L for oil and extract respectively. The study reveals that oil, was dominated by monoterpene hydrocarbons (44.99%) followed by oxygenated monoterpenes (13.66%) and Sesquiterpene hydrocarbons (16.59%). Among them, limonene (18.92%), α-pinene (13.94%), β- caryo phyllene (6.93%) and terpinen-4-ol (5.57%) were identified as major components. The Pistacia lentiscus oil and extract acts a mixed inhibitor and showed a result of the growth in the compactness of the protecting film dressing. The organic oil and extract adsorbs on the mild steel surface according to a Langmuir isotherm adsorption model.