The present invention describes a fragrance delivery system which releases fragrant aldehydes or ketones and/or fragrant compounds containing an olefin function upon exposure to light. This system comprises .alpha.-keto esters of formula ##STR1## in which R'* and R"* have the meaning as defined in the application and which are generally, in case of R'*, an alkyl group carrying an abstractable hydrogen in .gamma.-position relative to the .alpha.-keto function and carrying a moiety from which is derived a fragrant compound containing an olefin function, and, in case of R"*, the organic part of a primary or secondary alcohol from R"*OH which is derived a fragrant aldehyde or ketone.