Weight loss and polarization techniques have been used to investigate the rates of dissolution of copper single crystal (100), (110) and (111) planes in 0·1 M H₂SO₄ as well as in the presence of various concentrations (10⁻⁵M to 10⁻²M) of 2-mercapto pyrimidine (2-MP). The corrosion rates of copper single crystal plane were controlled by surface reaction which was found to be a function of crystallographic orientation, temperature and concentration of 2-MP. The stabilities of the crystal planes in pure acid were found to be (111)>(100)>(110). However, at the critical concentration of 2-MP (10⁻²M) the order of stability was found to be (110)>(100)>(111). The observed corrosion data revealed that inhibition of copper corrosion takes place by surface adsorption of inhibitor molecules, indicating a Bockris-Swinkels type of adsorption isotherm. Inhibitor efficiencies derived from weight loss and polarization techniques showed good agreement. The order of stability of the crystal planes was further confirmed by surface topographical changes during corrosion and also by the thermodynamics of adsorption of inhibitor molecules.