There are data dedicated to the features of synthesis of glasses in the system of bismuth borates introduced in the paper. It was shown that an increase of melt cooling rate leads to widening of glass-forming region: at a cooling of melt in crucible glasses forms in concentration area 35 – 45 mol.% Bi₂O₃, quenching on the metal plate yield glasses at 30 – 55 mol.% Bi₂O₃ area, and squeezing of melt between cold copper plates yield glasses at 30 – 70 mol.% Bi₂O₃ area. Concentration dependences of molar volumes of glasses were measured and partial molar volumes of bismuth and boron oxides were calculated. In agreement with FTIR spectroscopic data confirmed decrees or boron coordination number from 4 to 3 with increase of containing of bismuth, conversion occurs gradually at concentration 40 – 50 мол.% Bi₂O₃. In non-isothermal routine the apparent activation energy of glass crystallization was evaluated, it was shown that with addition of boron oxide that value decreases and crystallization temperature increases.