Novel inorganic ion exchange materials CsTreat(R), CoTreat, CsFloc and CoFloc were tested as precoat filter materials for the removal of radiocobalt and radiocesium from simulated radioactive waste liquids. Experiments were carried out in laboratory scale (120 cm(2) Millipore filter unit) and in pilot-scale (10 in. precoat cartridge). The decontamination factors for Cs-134 and Co-57 tracers was found to increase with increasing tracer feed activities, exceeding a value of 1000 at high feed activities. Kinetic analysis indicated that the kinetic mechanism of the radionuclide uptake in the powdered precoat materials was controlled by film-diffusion. Radiocesium removal was rather insensitive to solution chemistry but radiocobalt uptake was clearly decreased by increasing calcium content of solution. In addition, radiocobalt uptake had a maximum in neutral solution pH. Application of the inorganic ion exchangers as precoat materials looks to be a promising technique for the treatment of nuclear waste effluents (e.g., pond waters and nuclear power plant floor drain waters), enabling much faster flow rates than conventional column operation with granular materials. (C) 2004 Elsevier B.V. All rights reserved.