The simultaneous adsorption of Cu2+ and organic ligands L (L : 2,2’-bipyridyl (BIPY), 8-aminoquinoline (AQ), and o-phenylenediamine (OPDA)) in 0.1 M (K)NO3 or 0.1 M (Na)ClO4 solutions at TiO2 was investigated at 298.2 K. The experiments were performed by alkalimetric titrations. The experimental results for TiO2 are explained by assuming the formation of ternary surface complexes according to the general equation >SH2 + pH(+) + qCu(2+) + rL = >SH(2+p)Cu(q)L(r)((p+2q)+), where >SH2 denotes an uncharged surface site. The stability of these complexes as defined by the stability constants beta(p,q,r(int))(S) = [>SH(2+p)Cu(q)L(r)((p+2q)+)]/[>SH2][H+](p)[Cu2+](q)[L](r) e((p+2q)F psi/RT) was found to be (a) for L = BIPY, log beta(0,1,1,(int))(S) = 11.37, log beta(-1,1,1,(int))(S) = 6.00, log beta(-2,1,1,(int))(S) = -1.57, (b) for L = AQ, log beta(0,1,1,(int))(S) = 9.80, log beta(-1,1,1,(int))(S) = 4.11, log beta(-2,1,1,(int))(S) = -2.78, and (c) for L = OPDA, log beta(0,1,1,(int))(S) = 8.52, log beta(-1,1,1,(int))(S) = 1.86, log beta(-2,1,1,(int))(S) = -4.75. The possible structures of the postulated complexes are discussed.