Complex processes of charge transfer and phototransfer with complex changes in the distribution of charges in the system take place in chemical, electrochemical, photochemical, and photoelectrochemical systems. Today, complex processes for the production of hydrogen and methane using solar energy, biomaterials, algae, etc. are becoming relevant. A detailed analysis of the charge transfer and phototransfer process shows that the process is largely determined by the medium. In this regard, in particular, the process of photodissociation in the volume of an electrochemical system with subsequent electrochemical processes is of interest. The first considers the processes of photodissociation as a result of irradiation. In this case, charged ions (cations and anions) obtained by absorbing a photon with a certain frequency by a particle in the electrolyte are formed in the volume between the electrodes. The concentration of the appeared ions can be estimated using quantum chemical calculations or measured experimentally by spectral methods. The second segment involves the further movement of the formed ions in the volume of the electrochemical cell in the direction of the corresponding electrodes, which can also be calculated by quantum methods with the estimation of the characteristic parameters of the process, or experimentally measure the current density between the electrodes.