Depending on the style historic era, the religious tradition, of the authors' ideas, the requirements and technical capabilities of construction, the formation of the light-spatial composition of the church is more or less realized as an independent goal in the context of the overall spatial design of the church building. The purpose of the study is to identify the characteristic features of the formation of light-spatial composition in the space of Ukrainian Baroque churches in comparison with the features of the formation of the light environment of European Baroque churches. It has been found that the architectonics of the interiors of European Baroque churches and their light and space composition are united in their attempt to make a strong impression on a person. This impact is provided by the rich plasticity of the wall surfaces: the alternation of convex and concave tectonic elements, a complex play of light and shadow on the decorated surfaces. People's attention is focused not on a single tectonic form, but on their spatial arrangement, the effect of visual enlargement or reduction. Light begins to play the role of an independent component in the architectonics of the church. Different strengths of light accents set the scene for the visual perception of the church interior. It was found that the light-spatial composition inherent in Ukrainian Baroque churches does not create a theatrical effect. Centripetal light streams penetrating through the windows in the walls of the building from different directions create a relatively uniform brightness in the field of view without illusory light effects This nature of the distribution of light streams is more in line with the Renaissance idea of forming the light-spatial composition of the church. The upper space of churches is dominated by light from the windows of the light drums of the domes, focusing human attention on the semantic and compositional center of the building – тthe main dome. Light streams entering the church space through the windows in the domes and windows in the walls create a circular/round lighting pattern.