Urban plants play a significant role in shaping the microclimate of the modern city, in addition to the recreational and aesthetic functions. Climate change and sharp changes in temperature affect the plant growth and development, so the question of studying the adaptive potential of the plant range in cities to temperature variability is relevant and important. Researchers and scientists around the world are studying the impact of biotic and abiotic factors on plants, but the variability of the plant organisms in the urban ecosystem is still unexplored. The data from the analysis of the frequency of occurrence plants in Kyiv green spaces show that Tilia cordata Mill., Aesculus hippocastanum L., Spiraea×vanhouttei (Briot) Zabel. and Carpinus betulus L. are most represented among the researched species. The article presents the results of the assessment of heat resistance by using the method of Matskov (1976) of 13 ornamental woody and shrubby species. Besides, the plants were separated into groups of tolerance to high temperatures. It was established that the T. cordata plants are characterized by the highest indicators of heat tolerance and they can be recommended for the creation of open landscapes. The A. hippocastanum, Catalpa bignonioides Walt., S. vanhouttei and Forsythia europaea Degen & Bald. plants are characterized by ‘moderate tolerance’ indicators to high temperature stress, therefore they can be recommended for the creation of semi-open/open landscape types. Consequently, for the formation of semi-open landscapes, using the species Platanus occidentalis L., Quercus robur L., Q. rubra, Syringa vulgaris L., Berberis thunbergii DC. and Ligustrum vulgare L. which were assessed as ‘moderately sensitive’, is recommended. The leaves of the Carpinus betulus L. and Ribes aureum Pursh. plants were most vulnerable to high temperature stress; therefore, the species are recommended for the formation of closed landscape types. Despite the comparative classification of ornamental plants in terms of heat-resistance, many issues remain unstudied and need to be clarified in terms of ecology, physiology, biochemistry and phytopathology for the plants of urban green spaces.