The South American Spongeplant (Limnobium laevigatum (Humb. & Bonpl. ex. Willd.) Heine) is a floating aquatic plant native to freshwater habitats of tropical and subtropical Central and South America. It is frequently used for ornamental purposes in ponds and aquariums, and became invasive in the recent decades around the world. It has a high reproductive potential and a high dispersal capacity as well. It can form massive floating mats causing light limitation and creating anoxic conditions in the underlying water column, which strongly reduces native animal and plant biomass and diversity. It can also hamper navigation and water flow in rivers and canals. It has been introduced to the United States, Australia, Indonesia, Japan, Zambia and Zimbabwe. There is only one previous record in Europe (Belgium). This article is about the first record of Limnobium laevigatum in Hungary. I found two localities situated near Tata-Naszály and Dunaalmás (North-western part of Hungary). Both localities are fed by hot-water springs. It forms a small but dense population in Dunaalmás located near to the hot spring. The population in Tata-Naszály can be found in a 1.3 km long section of a stream, where it formed a sparse population in 2018.