Hospital waste incinerator (HWI) bottom ash was converted into a low-cost adsorbent, characterized and used for the removal of Remazol Brillant Blue Reactive (RBBR) from an aqueous solution. The adsorbent was obtained from incinerated hospital waste (Mascara, Algeria). The dye RBBR was adsorbed onto raw (RB) and treated bottom ash (TB). The material was characterized by X-Fluorescence, Scanning electron microscopy (SEM), Specific surface area (BET method) and pH(PZC). The results indicated that this material consisted of silica, carbonates and sodium chloride. Batch adsorption experiments were conducted to determine the effect of pH, contact time and initial concentration. The adsorption capacity was found equal to 269.36 mg/g and 275.4 mg/g for RB and TB, respectively.The adsorption data was fitted with the linear forms of the Langmuir, Freundlich and Dubinin–Radushkevich (D-R) models. The results indicated that the Langmuir adsorption isotherm provided a very satisfactory description of RBBR adsorption on both types of bottom ash. This adsorption process is physical in nature according to D-R equation. The adsorption reaction follows the pseudo-second-order kinetic. The thermodynamic constants obtained revealed that the process was spontaneous and endothermic for both materials.