AbstractFriction spot joining (FSpJ) is an advanced, alternative technology suitable for joining metal-composite overlap structures. In this paper, the principles of the FSpJ technique are briefly described. Furthermore, the influence of aluminum surface pretreatments (conversion coating and phosphoric acid anodizing) on the adhesion between aluminum alloy AA2024-T3 and carbon-fiber-reinforced poly(phenylene sulfide) (CF-PPS) friction spot joints was examined. X-ray photoelectron spectroscopy (XPS) was used to investigate the changes in the chemical composition of the aluminum after surface pretreatments, as well as chemical bond formation at the interface between the aluminum and composite. The joints were mechanically loaded until failure, and the fracture surface of the joints were analyzed on the aluminum side. XPS results showed evidence of Al–C and Zr–C bond formation at the interface for the selected surface pretreatments in the course of the joining cycle. Chemical bond formation was confirmed through the analysis of C1s and Al2p regions in which the appearance of new peaks with different binding energies compared with the aluminum and composite were identified.