The heterobifunctional linker DBCO-C6-Alkyne contains an Alkyne and a DBCO moiety which enable the possibility to perform two sequential click reactions in an orthogonal way. Therefore this linker offers a great potential to cross link to azide containg biomolecules by just using high efficient Click Chemistry. There is also the possibility to selectively click the alkyne before the DBCO [1]. Therefore this linker offers great potential for the synthesis of Antibody-drug-conjugates (ADC).