A process for exothermic treatment and recovery of masses including: urban solid waste (USW), including differentiated and non-differentiated damp waste and non-differentiated waste of vegetable origin; sludge generated by industrial and non-industrial water treatment; solid, semi-solid, pasty residue and/or sludge residue coming from industrial, agricultural and food-processing operations; soils and inert materials contaminated by organic matrices; solid, semi-solid, pasty residue and/or sludge residue of hydrocarbon compounds, including asphalt and organic-chemical compounds; contaminating animal excrements, such as those of poultry and/or swine. In particular, the process envisages the use of an exothermic reaction produced by mixing the mass to be treated with a mixture of calcium oxides (CaO) and/or calcium hydroxides Ca(OH)2, in the presence of an inert catalyst moistened with water, in the absence of oxygen using the charcoal-pile technique.