Provided are sulfonyl indolyl or sulfonyl indolinyl hydroxamates of formula (I), where R1 is sulfonyl substituted with alkenyl, alkynyl, phenyl, heteroaryl, cycloalkyl, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl and the other substituents are as defined in the specification. Examples of the compounds include 1-benzenesulfonyl-1H-indole-5-carboxylic acid hydroxyamide and 3-(1-benzenesulfonyl-1H-indol-5-yl)-acrylic acid. The compounds are inhibitors of histone diacetylases (HDAC). The compounds may be useful in the treatment of cancer.
