ask-fickleaura-mod-blog answered your question: Would a Dementor’s Kiss work on a Horcrux?

no. it didn’t work on harry.

It very nearly did though.  Harry was very susceptible to Dementors in general in his third year, and the only reason the kiss didn’t work on him was because he’s always repelled Dementors with a Patronus before they could actually kiss him.