URBAN LIGNOCELLULOSIC BIOMASS (ULB), DERIVED FROM THE MAINTENANCE OF PUBLIC AND PRIVATE GREEN SPACES, SUCH AS PARKS, GARDENS, SPORTS FACILITIES, AND AREAS ALONG ROADS, EMERGES AS A SOLID ALTERNATIVE TO REPLACE FOSSIL SOURCES. THESE RESOURCES STAND OUT DUE TO THEIR ABUNDANCE, LOW COST, AND AVAILABILITY. HYDROTHERMAL CARBONIZATION (HTC) EMERGED AS AN EFFICIENT TECHNOLOGY TO PROCESS THIS BIOMASS THAT HAS A HIGH MOISTURE AND ASH CONTENT, ELIMINATING THE NEED FOR PRIOR DRYING. THIS ARTICLE REVIEWS THE CONVERSION OF ULB TO SOLID BIOFUELS THROUGH THE HTC PROCESS, ADDRESSING THE PHYSICOCHEMICAL AND ENERGETIC PROPERTIES OF ULB AND THE RESULTING HYDROCHAR, AS WELL AS THE HTC PROCESS AND THE INFLUENCE OF THE OPERATING VARIABLES THAT AFFECT THE ENERGETIC QUALITY OF HYDROCHAR. THE CARBONIZATION TEMPERATURE (180 TO 280 °C) HAS A VERY SIGNIFICANT INFLUENCE MORE THAN THE RESIDENCE TIME (0.5 TO 24 H) ON...