A polyphasic approach was used to characterize a bacterium, GPTSA 11(T), isolated from a warm spring located in a reserve forest in Assam, India. The cells are Gram-variable, strictly aerobic, sporulating motile rods. The major fatty acids of the strain are C(15 : 0) anteiso (48.42 %), C(16 : 0) iso (11.59 %), C(16 : 1)omega11c (6.16 %), C(15 : 0) iso (6.03 %), C(17 : 0) anteiso (5.68 %) and C(16 : 1)omega7c alcohol (5.01 %). The presence of the fatty acid C(16 : 1)omega7c alcohol distinguishes this strain from other closely related species of the genus Paenibacillus. The strain contains MK-7 as the diagnostic menaquinone. The G+C content of the genomic DNA is 41.2 mol%. Analysis of the 16S rRNA gene sequence (1466 nt) revealed the presence of signature sequences PAEN 515F (5'-GAGTAACTGCTCTCGGAATGACGGTACTTGAGAAGAAAGCCCC-3') and PAEN 862F (5'-TCGATACCCTTGGTGCCGAAGT-3'), which were found in the species of the genus Paenibacillus surveyed by Shida et al. [Shida, O., Takagi, H., Kadowaki, K., Nakamura, L. K. & Komagata, K. (1997). Int J Syst Bacteriol 47, 289-298]. The sequence shows closest similarity (95.85 %) to that of Paenibacillus apiarius, followed by Paenibacillus alvei (94.34 %), Paenibacillus cineris (93.87 %), Paenibacillus favisporus (93.80 %), Paenibacillus chibensis (93.47 %) and Paenibacillus azoreducens (93.40 %). Biochemical, physiological, chemotaxonomic and phylogenetic analyses justify placement of the strain in the genus Paenibacillus but not within any existing species. It should, therefore, be considered as representing a novel species, for which the name Paenibacillus assamensis sp. nov. is proposed. The type strain is GPTSA 11T (=MTCC 6934T=JCM 13186T).