In this paper was studied the uranyl ions biosorption on three types of alga: Nostok linckia, Porphyridium cruentum and Spirulina platensis. These ions were supplied either from a pure solution of uranyl nitrate, or after leaching process of uranium ore, or from the sludge resulting in the output of pure UO2 technology. It was investigated the retention degree versus contact time and afterwards the Langmuir and Freundlich biosorption isotherms of uranyl ions on the three alga types. The retention of UO22+ ions on alga was proved through FTIR spectra plotted before and after biosorption processes. From the experimental data it was found that regardless of origin of uranyl ions, the retention degree on alga decreased in the series. Spirulina platensis > Porphyridium cruentum >= Nostok linckia. (C) 2012 Elsevier Ltd. All rights reserved.