By use of a surfactant-ion-selective electrode, potentiometric titration was done by adding tetradecyltrimethylammonium bromide (TTAB) to a solution of alpha-, beta-, or gamma-cyclodextrin (CD). Association constants have been determined for (TTAB)(x)(CD)(y) complexes, where both x and y are 1 or 2. It has been found that alpha-CD forms 1:1 and 1:2 TTAB/CD complexes, beta-CD forms only the 1:1 complex, and gamma-CD forms the 1:1 and 2:1 TTAB/CD complexes. The results are explained in terms of the difference in the cavity size of the CDs. The association constant values are compared with literature values for relevant systems.