Among a large collection of Tunisian hot springs bacterial isolates a bacterial strain, THE22T, with xylanolytic properties was identified. The bacterium was isolated from a natural hot spring “Ain Echefa” at Mediteranean sea (Korbous, North‐Eastern Tunisia). The novel strain was Gram positive, spore‐forming, rod‐shaped, facultatively anaerobic and grew optimally under conditions of 55 °C, 1% (w/v) NaCl and pH 7–8. The 16S rRNA gene sequence analysis showed that strain THE22T fell within the radiation of the cluster comprising Paenibacillus species with Paenibacillus phyllosphaerae PALXIL04T as the closest phylogenetic neighbour (95.8%). The predominant components in the fatty methyl ester profile were iso‐C16:0 (34.46%), C16:0 (19.64%), anteiso‐C15:0 (19.18%) and anteiso‐C17:0 (18.11%). The major respiratory quinone was menaquinone‐7 (MK‐7). The diamino acid found in the cell‐wall peptidoglycan was meso‐diaminopimelic acid. The base composition of DNA was 56 mol%. Based on the polyphasic taxonomic data, strain THE‐22T (=DSM 18499T = LMG 23758T) was recognized as a novel species within the genus Paenibacillus. The name Paenibacillus marinum sp. nov. is proposed.