Possibilities are demonstrated of varying the modes and conditions of anodic electrocrystallization in order to modify the mechanism of this process and to obtain, together with Tl2O3, other oxide phases on different substrates from Tl+ solutions. Using the methods of voltammetry, chronopotentiometry, gravimetry, Auger spectroscopy, and X-ray diffractometry, individual phases of thallium peroxide, a mixed-valence oxide, cuprate, and oxyfluoride synthesized by this process were characterized. For the first time, the boundaries of the thermodynamic stability regions were estimated for poorly studied thallium oxide phases in aqueous solutions.