A Gram-positive, rod-shaped, xylanolytic, spore-forming bacterium, strain GTH-3(T), was isolated from a tidal flat adjacent to Ganghwa Island, Republic of Korea, and was characterized to determine its taxonomic position. On the basis of 16S rRNA gene sequence similarity, strain GTH-3(T) was shown to belong to the family Paenibacillaceae, being most closely related to the type strains of Paenibacillus ginsengisoli (94.9 %), Paenibacillus anaericanus (94.8 %), Paenibacillus urinalis (94.4 %), Paenibacillus cookii (94.2 %), Paenibacillus alvei (94.1 %) and Paenibacillus chibensis (94.0 %). The G+C content of the genomic DNA of strain GTH-3(T) was 45.9±0.2 mol% (mean±sd). The major menaquinone was MK-7. The major fatty acids were anteiso-C(15:0) and iso-C(16:0). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phenotypic and chemotaxonomic data supported the affiliation of strain GTH-3(T) to the genus Paenibacillus. The results of physiological and biochemical tests allowed strain GTH-3(T) to be distinguished genotypically and phenotypically from recognized species of the genus Paenibacillus. Strain GTH-3(T) is therefore considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sediminis sp. nov. is proposed. The type strain is GTH-3(T) ( = DSM 23491(T) = LMG 25635(T)).