The behaviour of mild steel in 33% NaOH solution at 100°c has been studied. The current in the passive range may vary from 0·1 mA/cm2 cathodic to 1·0 mA/cm2 anodic. This is due to variations in the degree of cathodic depolarisation by oxygen and explains discrepancies in previously published data. The reduction in corrosion rate obtained by anodic passivation is not particularly high and would be practicable only in unusual conditions.
