Hydroxypropyl-beta-cyclodextrins (HP beta CD) which form 1:1 host-guest inclusion compounds with bithiophene (BT) are used for the anodic electropolymerization of bithiophene in aqueous solution. Partial encapsulation of the polymer chains by cyclodextrins is suspected from the quartz balance response during polymer reduction by cyclic voltammetry or double-step chronoamperometry. In this case, relatively thin films containing more than one HP beta CD molecule for ten BT monomers are formed on platinum electrodes. On the other hand, HP beta CD insertion or adsorption in the oxidized form of the polymer, obtained under galvanostatic or potentiostatic conditions, was found to be dependent on experimental conditions (long polymerization time). These results tend to confirm that polymerization occurs outside the CD cavity and that cyclodextrin insertion may occur by chain encapsulation after the polymer formation,