Bauxite ore processing industry in West Kalimantan generates a voluminous waste that posses potential environmental risks due to its high pH and mineral contents. However, the substantial presence of calcium, silica, aluminum, and iron in the bauxite ore processing waste (BOPW) also presents opportunities for beneficial utilization. This study investigates the potential use of BOPW as liner material in municipal solid waste landfills, in order to minimize groundwater contamination risk. Physical, chemical, mineralogical, and environmental characteristics, which comprise water content, specific gravity, particle size, toxicity characteristic leaching procedure (TCLP), atterberg limit, compaction, consolidation were measured using relevant ASTM and USEPA methods. The results showed that the BOPW exhibited favorable properties as landfill liner. The low moisture content (20.35%), cohesiveness, and specific gravity of 2.94, low hydraulic conductivity (7.56 ×10-7 cm/s) suggested suitability of the BOPW for landfill liner. Chemical analysis revealed predominant components of Fe₂O₃, Al₂O₃, SiO₂, and Na₂O, while mineralogical examination identified the presence of quartz, magnetite, hematite, and lime. The high pH value (11.93) supported chemical stability and immobilization of heavy metal contaminants. Despite favorable results of TCLP test, leachate quality analysis revealed elevated sodium concentrations (266 mg/L), which raised concerns about potential impact on surface water quality, particularly with the absence of specific regulatory standards. This study highlights BOPW's potential as a suitable landfill liner material, although further assessment for its long-term performance and application suitability is needed.