A new method to study ternary surface complexes at liquid-solid interfaces, the E(%)-pH curve method, is proposed, Three types of E(%)-pH curves, namely left-right shifts of S-shaped curves, V-shaped curves, and monodirectionally shifted curves, are postulated. Correspondingly, in addition to the Type I ternary surface complex [GRAPHICS] and the Type II ternary surface complex [GRAPHICS] a new type of ternary surface complex, [GRAPHICS] is proposed.