As Se-supplements became most popular during recent years, there is an urgent need for adequate analytical methodology for the identification and quantification of Se-species in Se-rich and enriched products.A method based on the coupling of Liquid Chromatography to both elemental (Inductively Coupled Plasma) and molecular (Electrospray Ionization) Mass Spectrometry was developed.This combination allowed the identification and on-line monitoring of Se-species in a diversity of food sources without the need for extensive sample preparation.In this presentation the focus will be on the Se-compounds present in Brazil nuts [1] and garlic [2], two natural products known to be rich in Se.They distinguish, however, from each other in the way Se is metabolized in their tissues.This results in different Se-compounds for consumption.The combination of LC-ICP-MS and LC-ESI-MS-MS allowed the identification of Se-Methionine in both Brazil nuts and garlic.The use of the Se-isotopic pattern aided in the identification of Se-Cystine in Brazil nuts.Se-MethylSeCysteine and the dipeptide γ-glutamyl-Se-MethylSeCysteine were identified in the garlic extracts without the need for a synthesized standard.This method can be applied in the identification of Se-species in new Se-fortificants and for the analysis of Se-metabolites after consumption of Se-rich food [3].