Two Gram-stain positive, rod-shaped, endospore-forming, aerobic, thermophilic strains, designated FJAT-2464T and FJAT-52740, were isolated from the sediment collected from Zhangjiang Estuary Mangrove National Nature Reserve in Fujian Province, China. The 16S rRNA gene sequence similarity between strains FJAT-2464T and FJAT-52740 was 100%. The result suggests that strains FJAT-2464T and FJAT-52740 belong to the same genome species, hence only FJAT-2464T was considered for further analysis. Strain FJAT-2464T showed the highest 16S rRNA gene sequence similarities to the type strains of Neobacillus thermocopriae SgZ-7T (99.9%), Neobacillus cucumis AP-6T (97.6%) and Neobacillus drentensis LMG 21831T (97.5%). Growth was observed at 25-65 °C (optimum 60 °C), pH 7.0-8.0 (optimum 8.0) with NaCl tolerance up to 1.0% (w/v) (optimum without NaCl %). The cell-wall peptidoglycan contained meso-diaminopimelic acid and MK-7 was the only respiratory quinone. The major fatty acids were iso-C15:0 and anteiso-C15:0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified aminophospholipid and unidentified lipids. The average nucleotide identity and digital DNA-DNA hybridization values between strain FJAT-2464T and the most closely related strain N. thermocopriae SgZ-7T was below the threshold value for species delineation. Based on the above results, strain FJAT-2464T represents a novel species of the genus Neobacillus, for which the name Neobacillus sedimentimangrovi sp. nov. is proposed. The type strain is FJAT-2464T (= MCCC 1K04406T = KCTC 43264T).