Abstract: Ability to eliminate reactive oxygen species is one of the most promising features of organoselenium compounds in medicinal chemistry. Ebselen (N-phenyl-1,2-benzisoselenazol-3(2H)-one) is a well known GPx mimic with proven antioxidant capacity. However, side effects, and in some cases only moderate activity, leave the search for new highly effective benzisoselenazolone analogues still open. In this work, we present an efficient methodology for the synthesis of ebselen derivatives. Lithium diselenide formed in situ reacts with N-substituted o-iodobenzamides to give the products in high yield - up to 98%. All synthesised compounds were also tested for their antioxidant activity in an NMR assay using dithiothreitol as substrate. The obtained results led us to the conclusion that N-phenyl analogues with p-methoxy, p-nitro and p-iodo moieties are the most active ones.