In this work, we performed comprehensive research combining voltammetric and UV-Vis absorption spectroelectrochemical techniques. Using voltammetry, we characterised the oxidation and reduction processes of TDMQ20 in detail and investigated the influence of pH on the redox reactivity of the tested molecules. Moreover, we have performed bidimensional thinlayer UV-Vis spectroelectrochemical experiments (Bidim-SEC). In a single Bidim-SEC experiment, two optical arrangements, normal and parallel, were used. The normal configuration, in which the light beam strikes perpendicular to the electrode surface, allows us to obtain information about both the diffusion layer and possible adsorption processes of TDMQ20 on the electrode surface. Parallel configuration, in which the light beam passes parallel to the electrode surface, provides information about changes to the tested compounds only in a small confined space adjacent to the working electrode surface. Scheme 1. Structure of TDMQ20 molecule and Cu(II)-TDMQ20 complex.