Strains 19SMN4T and ST27MN3 were isolated from marine sediments after enrichment with 2-methylnaphthalene and were classified as Pseudomonas stutzeri genomovar 4. Four other strains, BG 2, HT20, HT24, and A7, were isolated from sulphide-oxidizing bioreactors or activated sludge affiliated with the same clade in the 16S rRNA phylogenetic tree. P. stutzeri has been recently reclassified as a new genus, Stutzerimonas, and a preliminary analysis indicated that the strains in this study were distinct from any classified Stutzerimonas and are considered representatives of phylogenomic species 4 (pgs4). Strains 19SMN4T and ST27MN3 were extensively characterized with phenotypic, chemotaxonomic, genomic and phylogenomic data. Strain 19SMN4T had a well-characterized naphthalene degradative plasmid that has been compared with other plasmids, while in strain ST27MN3, the naphthalene degradative genes were detected in the chromosome sequence. Phylogenomic analysis of the core gene sequences showed that strains 19SMN4T and ST27MN3 shared 3,995 genes and were closely related to members of the species “Stutzerimonas songnenensis” and Stutzerimonas perfectomarina, as well as to the Stutzerimonas phylogenomic species, pgs9, pgs16 and pgs24. The aggregate average nucleotide identity (ANI) indicated that strains 19SMN4T and ST27MN3 belonged to the same genomic species, whereas the genomic indices with their closest-related type strains were below the accepted species threshold (95%). We therefore conclude that strains 19SMN4T and ST27MN3 represent a novel species of Stutzerimonas, for which the name Stutzerimonas decontaminans is proposed; the type strain is 19SMN4T (=CCUG44593T= DSM6084T=LMG18521T).