Abstract: In this study, a simple one-step hydrothermal method was developed to synthesize oxygen-incorporated molybdenum disulphide (O-MoS₂) nanoflowers, which possessed a new structure with the enlarged (002) interlayer spacing of about 10.5 Å compared with the value of 6.15 Å for the pristine MoS₂, owing to the incorporation of oxygen atoms into the skeleton of MoS₂. Moreover, the sample of O-MoS₂ nanoflower exhibited extraordinary tribological performance as novel additive in poly alpha olefin base oil (PAO-8) because of smaller slip resistance of enlarged (002) planes. Experimental results indicate that the optimal concentration of the O-MoS₂ nanoflower in PAO-8 was 0.1 mg/mL.