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Structural and optoelectronic properties of α, \{beta}, γ phases of calcium titanate are studied with the implementation of first-principles quantum-chemical calculations in the framework of DFT. When optimizing the geometry, the GGA approximation was used. The relaxed lattice parameters obtained by us are identical with the experimental analogs. It has been established that the most stable phase of calcium titanate is the orthorhombic syngony, which corresponds to the results of experimental measurements. It is shown that as the transition from the α-phase to the γ-phase proceeds, the lattice constant parameters and the interatomic distance in these systems increase. The optoelectronic properties of these materials have been studied using the Wien2k code. The high-precision TB-mBJ approximation was used to calculate the exchange-correlation effects. An analysis of the electronic properties of these materials showed that all the studied phases of calcium titanate belong to the class of wide-gap semiconductors. The calculated band gaps for the cubic, tetragonal, and orthorhombic CaTiO3 systems are 2.83, 3.07, and 3.26 eV, respectively. According to the analysis of DOS-plots, it was found that the tetragonal phase of calcium titanate is characterized by the highest density of states. Calculations of the optical constants of the systems under study showed that the CaTiO3 cubic system is characterized by an increased absorption capacity and a relatively high photoconductivity. However, for the other two phases of calcium titanate, the calculations gave identical patterns, i.e., the absorption and optical conductivity spectra of the tetragonal and orthorhombic CaTiO3 systems practically coincide.