The inhibitive action of the aqueous extract of Melissa officinalis toward 
the corrosion of C-steel in a 2.0 M HCl solution was investigated using 
weight loss measurements and Tafel polarization curves . It found that the 
extract acts as good corrosion inhibitor for tested system. The inhibition 
efficiency increases with increasing extract concentration. The inhibitive 
action of the extract is discussed with a view to adsorption of its 
component s onto the steel surface, making a barrier to mass and change 
transfer. The adsorption of extract components onto the steel surface was 
found to be a spontaneous process and to follow the Langmuir adsorption 
isotherm.