Accurate identification of the Essential oil of aerial parts of Salvia Officinalis was obtained by hydrodistillation, was undertaken using GC and GC/MS (gas chromatography- mass spectrometry), followed by principal component analysis (PCA). The oil was predominated by α-Thujone (22.2%). The extract and Essential oil of S. officinalis leaves has been evaluated as a corrosion inhibitor for steel in 1 M HCl solution by means of weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract of S. officinalis acts as a mixed type inhibitor. Inhibition was found to increase with increasing concentration of the essential oil and extract of S. Officinalis. Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1M HCl with addition of essential oil and extract was also studied and thermodynamic parameters were determined and discussed