A convenient experimental method for thermodynamical studies based on partial-filling affinity CE is presented. The advantages of this approach are the possibility to determine binding energies from relatively weak interactions as well as the small amounts of samples consumed. In order to explore the affinity and selectivity of the cellobiolrydrolase Cel7A, a number of propranolol analogues were recently designed. The affinities of a selection of these ligands were determined in the temperature interval 15-40 degrees C, and Delta G degrees, Delta H degrees and Delta S degrees were obtained by means of Van't Hoff plots. Through these experiments, the importance of the entropy contribution in the complexation between the ligands and Cel7A has been demonstrated.