The fate of technetium (Tc) in the environment depends on its interaction with such minerals or microorganisms. In the last decades, research has been oriented towards the immobilization of inorganic Tc by reductants. However, much less is known about how metabolites (produced by microorganisms) could influence the interaction between Tc(VII) and Fe(II)-minerals and on the environmental behaviour of organometallic Tc. Hence, the factors influencing the mobility of Tc need to be studied in order to ensure the best conditions to prevent (or remediate) the emission of inorganic or organometallic Tc in the environment. The aim of this beamline proposal is analyzing the immobilization of inorganic TcVII (as TcVIIO4) by pyrite (FeS2) in presence of metabolites (acetate, succinate and siderophore). The kinetics of Tc removal by pyrite is slowered by succinate and acetate, while siderophore inhibits totally the removal of Tc.