This study describes the problems of managing biodegradable waste in the form of leaves in the thermochemical conversion process of waste biomass. The results of experimental studies of physicochemical properties of leaves of 4 selected tree species (i.e., oak, hazel, maple, and walnut) are shown. The study consisted of determining the energy parameters in the form of markings gross and net calorific value of the test material. In addition, the ash and moisture content of the material was tested. Moreover, an elementary analysis for the tested leaves by determining the content of carbon, hydrogen, and nitrogen was measured. The studies have shown great energy potential for the examined leaves, in particular oak leaves, where the gross calorific value amounted to 18.77 MJ·kg^-1, net calorific value of 17.70 MJ·kg^-1, and an ash content of 21.98%. Oak leaves are also characterized by the highest carbon content of 47.66%, hydrogen at 6.32%, 0.88% nitrogen, and sulfur 0.14%. Determined emission rates indicate a reduction of 28-35% CO, 24-53% NO_x, 26-32% CO₂, 53-60% SO₂, and 31-54% dust depending on the type of biomass used.