A description is given of the use of naphthalene-1,8-dicarboxylic
monoimides of the formula (I), in which R.sup.1 is hydrogen, alkyl,
alkenyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, aryl or heteroaryl
and R.sup.2 is a radical containing at least one .pi. electron system
containing a carbon atom and at least one further atom selected from
carbon, oxygen, and nitrogen, with the proviso that the radical contains
at least one atom other than carbon; to protect organic material from the
damaging effects of light, of compositions which comprise at least one
naphthalene-1,8-dicarboxylic monoimide of the formula (I) in an amount
which provides protection from the damaging effects of light, and at
least one organic material, and of new naphthalene-1,8-dicarboxylic
monoimides (I).