Corrosion is a gradual degradation of materials, usually metals by chemical reaction with its environment. Corrosion of metals constitutes a major problem facing most construction firms. In recent years, more efforts are directed towards investigation of mild steel corrosion perhaps due to increased technologically related applications of mild steel and metals in general for industrial and domestic purposes. This study investigates corrosion inhibition of mild steel by pyrimethamine in 2.0M HCl, by gravimetric analysis. Essential parameters like corrosion rate, percentage inhibition efficiency and degree of surface coverage were obtained from data generated experimentally. Facts gathered from analysis of generated data and review of related literature, revealed that; pyrimethamine significantly (p<0.5) reduced the corrosion rate of mild steel in 2.0M HCl. And that the reduction in corrosion rate significantly (p<0.5) increased with increased in inhibitor concentrations, but reduced with rise in temperature to values that tested non-significant (p<0.05) for temperatures ≥ 333K and inhibitor concentrations < 5.0 x 10-4M. Also, the corrosion rate increased with rise in temperature at all inhibitor concentrations. Percentage inhibition efficiency and degree of surface coverage were notice to increase with increase in inhibitor concentration but reduced with rise in temperature.
