A bacterial strain, designated Iso4T, was isolated from the East Sea of Korea and was subjected to a polyphasic taxonomy study including phenotypic and chemotaxonomic characteristics as well as 16S rRNA gene sequence analysis. Cells of the strain were Gram-negative, motile, non-budding, non-stalked, and strictly aerobic. Strain Iso4T grew optimally at 20°C in the presence of 1~2% (w/v) NaCl and at pH 6.9~7.6. The major respiratory quinone was Q-10 and the major cellular fatty acids were C18:1 ω7c (53.5%), C17:1 ω5c (11.7%), C17:1 ω6c (8.1%), C16:0 (7.8%), C17:0 (4.8%), C15:0 (2.9%), and C16:1 ω5c (2.2%). The DNA G+C content of strain Iso4T was 56.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain Iso4T formed a monophyletic clade in the family Hyphomonadaceae, supported by high bootstrap value and was most closely related to the genus Hyphomonas (92~94%), a member of marine bacteria in the family. The phenotypic, genotypic, and chemotaxonomic evidences also suggest strain Iso4T represents a novel genus and species in the family Hyphomonadaceae, for which the name Henriciella gen. nov., sp. nov. is proposed. The type strain is Iso4T (=KCTC 12513T =DSM 19595T =JCM 15116T).