Accurate identification of the Essential oil of aer ial parts of Salvia Officinalis was obtained by hyd rodistillation, was undertaken using GC and GC/MS (gas chromatograp hy- mass spectrometry), followed by principal compo nent 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 lo ss measurements, potentiodynamic polarization, electro chemical impedance spectroscopy (EIS). Tafel polari zation 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 e xtract of S. Officinalis. Values of inhibition effi ciency calculated from weight loss, Tafel polarization curves, and EI S are in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1M HCl with ad dition of essential oil and extract was also studie d and thermodynamic parameters were determined and discus sed