The corrosive effects of sulphate ions in alkaline media have not to date been clearly outlined or defined. Research of sulphate attack is at a critical stage. In spite of meaningful advances in the past few years, this problem is still not well understood. Extensive work by many researchers has been conducted on studies relating to the effect of chloride ions in acidic and alkaline media. The bulk of research work has been done in relation to stainless steels in the above-mentioned media. This research study aims to focus on a more commonly used construction material, mild steel, otherwise known as carbon steel, and to determine and define the effects of sulphate ions on their own and the effect of sulphate ions in the presence of chloride ions in alkaline media. Commercial grade mild steel was tested using the gravimetric and potentiodynamic methods, in alkaline solutions of varying concentrations of sulphate ions together with additions of different concentrations of chloride ions. Results show that mild steel material protection is seriously compromised when in the presence of highly basic media.