ZnSe2O5 nanocrystals with an orthorhombic structure were synthesized by electrochemical deposition into a-SiO2/n-Si ion track template formed by 200 MeV Xe ion irradiation with the fluence of 10 7 ions/cm 2. The lattice parameters determined by the X-ray diffraction and calculated by the CRYSTAL computer program package are very close to each other. It was shown that ZnSe2O5 has a direct band gap of 2.8 eV at the Γ-point. In addition, the calculated charge distribution and chemical bonds show that the crystal has an ion-covalent nature. The photoluminescence excited by photons at 300 nm has a low intensity arising mainly due to zinc and oxygen vacancies.