The dark degradation of tetraacetylethylenediamine (TAED) was investigated. It is a slow process which is favored in acidic medium. There is a hydrolysis of an imide group with the scission of the CN bond giving rise to the triacetyl derivative (TAED'). When allowed to stand for longer times a second acetyl group is eliminated with the formation of the symetric diacetyl derivative (DAED). The degradation of TAED photoinduced by iron (III) was also investigated. It appears a faster degradation which does not lead to the same products. The process only involves •OH radicals formed upon photolysis of aquocomplex of iron (III). They preferentially abstract a hydrogen from the methylene group. The degradation is then assisted by oxygen and leads to the formation of carbonylated oxidation products.