New thiazolo[5,4-b]azepine compounds represented by ##STR1## wherein R.sup.1 is a hydrogen atom, an aliphatic group which may be substituted, a carboxylic acyl group which may be substituted or a sulfonic acyl group which may be substituted; R.sup.2 is a hydrogen atom, an aromatic group which may be substituted or an aliphatic group which may be substituted, which are capable of e.g., inhibiting lipoperoxide formation.