This work investigates the behaviour of BDD samples differently aged by an oxidative treatment. Two series of data are presented: the first in acid solutions was used to derive information about the electronic structure of the samples, whereas measurements in equimolar ferro/ferri cyanide solutions were performed to test the activity of the samples towards charge transfer reaction. Flat band potential as well as energy levels of conduction and valence bands were calculated for new and aged samples. These parameters, together with the current voltage response, are crucial information for a comprehensive interpretation of the behaviour of samples.