Mineralogical and sorption capacity characteristics of Ankara Clay, which is widespread around the Ankara region, Turkey, have been studied for the purpose of its potential use as a landfill liner. This clay is Pliocene in age and was deposited in a fluvial environment. Mineralogically it consists mainly of illite, smectite, chlorite and kaolinite minerals. The non- clay minerals, quartz, feldspars, calcite and Fe-Ti oxides are detected. Its cation exchange capacity (CEC) is determined as 41 meq/100 g using the Ag-Tu method. The retention of the heavy metal cations follows the order of Pb2+ > Cu2+ > Zn2+ > Mn2+, Cd2+. These characteristics, together with its known engineering properties, suggest that Ankara Clay can be utilized as a component of a barrier system. These findings also indicate the potential usage of widespread occurring fluvial clays as landfill liners. (C) 2002 Elsevier Science Ltd. All rights reserved.