The hydroperoxy sultams (HPS) have been investigated in catalytic epoxidation reaction of cyclooctene. We have found that HPS can function as the epoxidation agents in the presence of molybdenum boride MoB as a catalyst. The reaction was sensitive to steric as well as electronic factors. The high epoxides yields were observed in the case of hydroperoxy sultams with chlorine atoms and especially favorable was hydroperoxide structure with alpha-position of chlorine atom to bond of nitrogen with aromatic ring. (C) 2007 Elsevier B.V. All rights reserved.