The inhibition of corrosion of mild steel in 0. 05 N HCl by non-ionic surfactants of the polyethylene oxide-fatty acid condensate type was studied using the weight loss technique at 70 degree C. The percentage inhibition (PI) increased with the increase of additive concentration up to values comparable with the CMC (critical micelle concentration) of the surfactant, whereby a constant efficiency is attained. Conformation with Langmuir adsorption iostherms suggested that these compounds effect corrosion inhibition by being adsorbed on the metal surface.