Electrical properties of TlBr purified by hydrothermal annealing in pure water were studied by I–V, capacitance and photocurrent measurements using Ti-electrodes which were deposited by electron-beam evaporation. Time characteristics of the current during the aging were recorded under fixed voltage (0–200V) at different temperatures 277–353K. The samples were additionally characterised by the X-ray powder diffraction and rocking curve methods. The degradation of TlBr was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The composition at the electrode area was observed to be different for the negative and positive sides.