– Suberoylanilide hydroxamic acid (SAHA) is a class I and class II histone deacetylase (HDAC) inhibitor that binds directly to the catalytic site of the enzyme thereby blocking substrate access. SAHA-BPyne is a SAHA derivative with a benzophenone crosslinker and an alkyne tag intended to be used for profiling HDAC activities in proteomes and live cells. Such terminal alkyne groups can be used in linking reactions, known as click chemistry, characterized by high dependability and specificity of azide-alkyne bioconjugation reactions. SAHA-BPyne labels HDAC complex proteins both in proteomes at 100 nM and in live cells at 500 nM and demonstrates an IC50 value of ~3 μM for inhibition of HDAC activity in HeLa cell nuclear lysates in an HDAC activity assay.