A novel strain of the class Actinobacteria was isolated from a seawater sample collected in the South China Sea using modified R2A agar plates. The strain was a Gram-stain-positive, nonmotile, non-spore-forming, catalase-positive, irregular rod-shaped bacterium. The strain grew at 4-45 °C and pH 5.0-10.2, and tolerated 5% (w/v) NaCl. Based on its 16S rRNA gene sequence, the organism was related phylogenetically to members of the genera Fodinibacter (96.7% similarity), Lapillicoccus (96.5 %), Knoellia (95.0-95.8 %), Oryzihumus (95.6 %) and Humibacillus (95.6 %). The cell-wall contained L-ornithine as the major diagnostic diamino acid in the peptidoglycan. MK-8(H₄) was the predominant menaquinone. Major cellular fatty acids were iso-C₁₈:₁ω9c, iso-C₁₆:₀, iso-C₁₅:₀ and C₁₇:₀. The G+C content of the DNA was 69.6 mol%. Phenotypic and phylogenetic data revealed that this strain represents a novel species in a new genus of the family Intrasporangiaceae, for which the name Ornithinibacter aureus gen. nov., sp. nov. is proposed; the type strain of Ornithinibacter aureus is HB09001(T) (=CGMCC 1.10341(T) =DSM 23364(T)).