The concn. and temp. dependent dimerization of 1,1'-diethyloxadicarbocyanine iodide (DODC) in aq. solns. of b-cyclodextrin (b-CyD) is studied by UV/vis and CD (CD) spectroscopy. The spectroscopic data are analyzed by singular value decompn. and yield equil. consts. in agreement with known values. Thermodn. parameters are obtained and discussed. The almost const. dissymmetry factor of the induced CD over the whole exptl. range is further evidence of a free monomer and complexed dimer of DODC.