Abstract: Selenium-based reagents bear a high potential for the improvement of known reactions not only from an environmental and pharmaceutical point of view, but also as interesting reagents for the development of, completely new synthetic transformations and as potential ligands in catalytic reactions. A variety of organoselenium compounds have been proven to be useful for organic synthesis over several decades. Organoselenium species can be introduced as either nucleophiles or electrophiles to other organic molecules, producing useful intermediates for organic synthesis. Optically active organoselenium derivatives and their application to highly selective asymmetric synthesis are also of current interest. Probably the most interesting aspect, which emerged in recent years, concerns the possibility of effecting some functional group conversions using catalytic amounts of the selenium reagent or using selenium containing compounds as chiral ligands in metal catalyzed reactions. The developments of all these catalytic processes represent the most important results which have been reported recently in this field and their conceptual and synthetic relevance considerably increases the use of some organoselenium derivatives as Green Catalysts. [1] In consideration that in Nature, the main biological function of selenium is associated with its incorporation in the form of selenocysteine (Sec) into certain proteins having redox motifs different selenium containing compounds can be investigated as bio-inspired catalysts in the carbon-carbon multiple bond oxidation mediated by H₂O₂ in water. These catalysts resulted to be also interesting good GPx-mimetics. Acknowledgement: Financial support from M.I.U.R.-PRIN2007, Consorzio CINMPIS, Bari, University of Perugia, the grant "British-Italian Partnership" from the British Council/CRUI. References [1] a) D. M. Freudendahl, S. Santoro, S. A. Shahzad, C. Santi, T. Wirth Angew. Chem. Int. Ed.2009, 8, 8409.b) C. Santi, M. Tiecco, L. Testaferri, C. Tomassini, S. Santoro, G. Bizzoca Phosphorus Sulfur Silicon Relat. Elem. 2008,183, 956. c) S. Santoro, C. Santi, M. Sabatini, L. Testaferri, M. Tiecco Adv.Synth. Catal. 2008, 350, 2881. d) S. Santoro, B. Battistelli, B. Gjoka, C-w.S.Si, L.Testaferri, M. Tiecco, C. Santi Synlett, 2010, 1402.