A novel alphaproteobacterium was isolated from the well water of a thermal bath at Budapest, Hungary. Phylogenetic analysis of the novel strain showed that this bacterium belongs to a distinct lineage among the genus Brevundimonas. Based on the 16S rRNA gene sequence strain FDRGB2bT showed the highest sequence similarity values to Brevundimonas naejangsanensis BIO-TAS2-2T (97.35 %), Brevundimonas viscosa F3T (97.28 %), Brevundimonas vesicularis LMG 2350T (97.27 %), Brevundimonas nasdae GTC 1043T (97.14 %), Brevundimonas vancanneytii LMG 2337T (97.13 %) and Brevundimonas aurantiaca DSM 4731T (97.13 %). The newly isolated bacterium was strictly aerobic, and its optimum growth occurred at 20-30 °C, between pH 8-9 and without NaCl. Movement was with a single polar flagellum, but the cells could also produce stalks. The major isoprenoid quinone of strain FDRGB2bT was Q-10, the major cellular fatty acids were C18 : 1ω7c and C16 : 0, and the polar lipid profile contained phosphatidylglycerol, diphosphatidylglycerol, two unknown phospholipids and four unknown glycolipids. The characteristic diamino acid in its cell wall is meso-diaminopimelic acid. The G+C content of DNA of the type strain was 69.8 mol%. Strain FDRGB2bT (=DSM 29841T=NCAIM B.02621T) is proposed as the type strain of a novel species with the proposed name Brevundimonas balnearis sp. nov.