A novel alphaproteobacterium, strain RAM11T, belonging to the family Rhizobiaceae was isolated from the pool water of a thermal bath in Budapest, Hungary. Based on the 16S rRNA gene sequence strain RAM11T shows the highest sequence similarity values to Ensifer adhaerens Casida A (97.44 %), to Ensifer (syn. Sinorhizobium ) americanus CFNEI 156T (96.87 %) and to Rhizobium azooxidifex Po 20/26T (96.76 %). The new bacterium is strictly aerobic, its optimum growth occurs at 20–37 °C, between pH 7 and 9 and without NaCl. It is motile due to a single polar flagellum, capable of budding and forms rosettes in liquid culture. The major isoprenoid quinone of strain RAM11T is Q-10, the major cellular fatty acids are C18 : 1 ω7c and 11-MeC18 : 1 ω7c. The polar lipid profile contains phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, an unidentified aminolipid and an unidentified phospholipid. The G+C content of DNA of the type strain is 62.9 mol%. Strain RAM11T (=DSM 29853T=NCAIM B.02618T) is proposed as type strain of a new genus and species with the proposed name Gellertiella hungarica gen. nov., sp. nov.