Recovering degraded soils is crucial to ensure food supply and security, preserve biodiversity, sequester carbon (C) to counter climate change, and regulate water and nutrient cycles. Mining is one of the worrying anthropogenic activities responsible for soil degradation because it is a major source of trace elements in the soil. An effective strategy to restore degraded soils may be the use of organic improvers. The aim of this study was to evaluate the effects of two organic improvers, hydrochar and compost, both deriving from urban pruning residues, on soil physical, chemical and biological properties. Compared to compost, which is a traditional organic improver, the hydrochar, obtained from hydrothermal carbonization, has recently been receiving much interest as a new potential soil improver. A pot experiment was carried out using soil collected from a contaminated site (the disused Mónica mine, Madrid, Spain). The experimental design included three treatments: soil + hydrochar (SH), soil + compost (SC), untreated soil (S) and two exposure times (t0 and t60 days). Preliminary results showed that both soil improvers, applied at the same dose (92.4 g kg^-1), significantly increased soil water retention, total organic carbon content and its available fractions (extractable C and mineralizable C), microbial biomass and enzyme activities (dehydrogenase, hydrolase and urease activities), with a marked effect only after 60 days. On the contrary, no effect of treatments was recorded on soil potential respiration. No univocal differences were found between the effects of the two improvers. Data suggest that both soil improvers can enhance soil health, also activating microbiological processes that are fundamental to soil resilience to disturbance. This work confirms the hypothesis that both organic materials derived by treatment of urban pruning residues could represent an effective and sustainable strategy for soil restoration, contributing to the regeneration of ecosystem services.