<p>This paper explores the synthesis, mechanical performance, microstructure, and leaching behavior of autoclaved bauxite residue (BR)-based monoliths. The monoliths were produced through a simple and robust Bayer process-inspired method consisting of the alkali activation of BR followed by pressing and hydrothermal curing in an autoclave. The precursor comprised 100 wt% of BR activated with Na silicate solution in a liquid-to-solid ratio (L/S) of 0.15. After mixing, cubic dense monoliths of 4 cm³ were press-shaped at 47&#xa0;MPa and autoclaved at 220&#xa0;°C and 24&#xa0;bar of steam pressure for 24&#xa0;h. The specimens were tested on compressive strength and the fragments were subjected to quantitative X-ray diffraction analysis (QXRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), N₂ adsorption, water absorption, and leaching tests. The results revealed that the hydrothermal curing promoted the reactivity of the precursor by facilitating the dissolution of gibbsite and quartz and the partial transformation of sodalite to cancrinite. Microstructural analysis showed the formation of a gel-like binder phase likely enriched in Na and Si. Such reactions enhanced the hydrolytic stability and the mechanical performance, with the autoclaved sample achieving a compressive strength of 31&#xa0;MPa (6 times higher than the non-autoclaved sample). The leaching tests showed that the release of potentially hazardous elements was reduced to levels below the European criteria for hazardous waste, a result attributed to the increase of surface area creating spaces for adsorption and the partial leaching of elements to the wastewater during autoclaving.</p> Graphical Abstract <p></p>