This study investigates the geotechnical properties, and mineralogical and permeability characteristics of "Ankara clay" to evaluate its suitability as a compacted clay landfill liner material. The geotechnical index properties of the clayey soil samples collected from the western part of Ankara were determined. All the soil samples were tested for permeability by means of falling head compaction permeameter apparatus. The mineralogy of the soil samples were examined by X-ray diffraction and scanning electron microscope analyses. The cation exchange capacities of the soil samples were determined by the methylene blue adsorption test in order to determine the presence of swelling clay minerals in the soil samples. The influences of the geotechnical indices and mineralogy of Ankara clay on the hydraulic conductivity were investigated. Several landfill profiles containing various compacted clayey lining systems were simulated by the Hydrologic Evaluation of Landfill Performance model. All the soil samples tested led to hydraulic conductivities lower than the suggested regulatory limits (1 x 10(-9) m/s) and therefore, are suitable to be utilized as compacted clay liners in potential sanitary landfill sites. Recommendations regarding field construction of the compacted clay liner are provided.