Taxonomic descriptions and a key are provided for species or the genus Kleidotoma Westwood known from Hawaii. Six species are treated, three of which are described as new. Two new species associated with endemic freshwater Ephydridae and Canaceidae are placed in a new subgenus, Nesakleidotoma. A third species, K. (Pentakleidota) swezeyi Yoshimoto, also may be aquatic and has been collected around brackish littoral ponds containing larvae of Neoscatella (Ephydridae). Of the remaining three species, all placed in the nominate subgenus, two have not been associated with aquatic environments and are presumed to be recent immigrants of unknown origin. One of these is described as new, and the second, K. kraussi Yoshimoto, was known previously only from Fiji. The third species, K. bryani Yoshimoto, previously known only from Hawaii and Palmyra, is here reported from Guam, where it was collected in association with beach seaweed.