Cobaltites-gallates in the binary system LaCoO3 – LaGaO3 are synthesized. X-ray phase analysis showed that a continuous series of solid solutions with the composition LaCo1 − x Ga x O3 is formed in the system investigated. It is determined that solid solutions with 0 < x ≤ 0.7 and 0.7 < x ≤ 1.0 possess rhombohedrally and orthorhombically distorted perovskite structure, respectively. Analysis of the dependence of the absorptionband frequency of the IR spectra of the solid solutions LaCo1 − x Ga x O3 which is due to stretching vibrations on the degree of substitution of Ga3+ ions for Co3+ ions in LaCoO3 showed that the morphotropic boundary separating the region of the solid solutions LaCo1 − x Ga x O3 with rhombohedrally and orthorhombically distorted perovskite structure passes near the composition of the solid solution with x slightly less than 0.7.