baseclick’s RNA Labeling Kit has been developed for the production of alkyne-labeled RNA targets by in vitro transcription from bacteriophage T7 RNA polymerase promoters. Because of the nature of transcription reactions, many RNA copies of the template DNA are produced. The kit utilizes 5-Ethynyl-UTP (5-EUTP) nucleotide to firstly label the RNA with alkynes. The resulting RNA contains alkyne modified Uracils, which react with azido-derivates of fluorescent dyes, haptenes and others in a highly selective fashion under benign click reaction conditions. The label incorporation can be tuned by the amount of marker azide used in the click reaction.