Glutathione peroxidase (GPX), an essential antioxidant selenoenzyme, protects living organisms from oxidative stress by catalyzing the reduction of potentially toxic hydrogen peroxide or lipid hydroperoxides at the expenses of reduced glutathione (GSH). Organochalcogens such as ebselen and diphenyl diselenide are well-known as synthetic GPx mimetic. Here we studied the GPx-like activity of new organochalcogens: 2-Amino-3-phenyl-propane-1-diselenide (1), and (2-Phenyl-1-Diselenenylmethyl-ethyl)-carbamic acid tert-butyl ester (2). Thiol-peroxidase activity of organoselenium compounds (15mM) was examined using benzenethiol (PhSH) as a glutathione alternative at different concentrations ( 0,5mM; 1mM; 2mM). The reduction of H₂O₂ (3mM) and oxidation of PhSH was monitored at 305nm (production of diphenyl disulfide, PhSSPh). ANOVA showed that compound (1) had an increased thiol-peroxidase activity at 1mM and 2mM concentrations of PhSH, when compared to compound (2) and diphenyl diselenide. Structure of compounds (1) is similar to that of compound (2), except that the –NH₂  near the selenium is BOC protected in compound (2). Thus, the blockage of the free amino group near the selenium atom  possibly hampered the thiol-peroxidase activity. Therefore, we concluded that the poor thiol-peroxidase activity of (2)  is related to the blockage of its –NH2, impeding  or disturbing  the interaction Se-N that is fundamental thiol-peroxidase activity of diorganoyl diselenides .