Novel Cu/nanoclay composites with antibacterial activity were synthesised by molten salt ion exchange method at two temperatures and at different times. The produced composites were characterised using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The antibacterial activity of these composites was assayed by the disc inhibition method. XRD patterns indicate that nanoclay has a d-spacing (1.44 nm), higher than Cu/nanoclay composites (1.34–1.37 nm). This result implies that copper nanoparticles could exist in microspores of nanoclay. On the other hand, the UV-Vis findings confirm that no copper in the form of sulfate existed in the obtained composites. The antibacterial activity of Cu/nanoclay nanocomposites against Escherichia coli and Staphylococcus aureus showed efficient bactericidal effect. On the other hand, results demonstrate that the antibacterial activity of the resultant composites does not depend on ion exchange time and temperature. Thus, the resultant composites show high stability that can last for a long time. The produced composites by this novel method can be used to synthesise nanoclay composite with antibacterial activity for various applications such as water treatment and biodegradable composites.