We provide the occurrence data on five newly recorded alien Hydrocotyle Tourn. ex L. species (Araliaceae) in Java, namely H. acutiloba (F.Muell.) N.A.Wakef., H. bonariensis Comm. ex Lam., H. leucocephala Cham. & Schltdl., H. tripartita R.Br. ex A.Rich., and H. verticillata Thunb. Most species were introduced as ornamental plants and naturalized in Java. Hydrocotyle acutiloba and H. tripartita might have been accidentally introduced as soil contaminants during the Dutch Colonial Era, but both species had been misidentified as H. sibthorpioides. Descriptions, a key, distribution map, and images of the species are provided.
