Silver-titania (Ag-TiO 2 ) nanoparticles with smaller Ag nanoparticles attached to larger TiO 2 nanoparticles were generated by hybrid ultrasonic vibration and picosecond laser ablation of Ag and Ti bulk targets in deionised water, for the first time. The laser has a wavelength of 1064 nm and a pulse duration of 10 ps. It was observed that without the ultrasonic vibration, Ag and TiO 2 nanoparticles did not combine, thus the role of ultrasonic vibration is essential. In addition, colloidal TiO 2 and Ag nanoparticles were generated separately for comparison under the same laser beam characteristics and process conditions. The absorption spectra of colloidal Ag-TiO 2 cluster nanoparticles were examined by UV-Vis spectroscopy, and size distribution was characterised using transmission electron microscopy. The morphology and composition of Ag-TiO 2 nanoparticles were examined using scanning transmission electron microscopy in highangle annular dark field, and energy-dispersive X-ray spectroscopy. The crystalline structures were investigated by X-ray diffraction. The size of larger TiO 2 particles was in the range 30-150 nm, and the smaller-sized Ag nanoparticles attached to the TiO 2 was mainly in the range of 10-15 nm. The yield is more than 50 % with the remaining nanoparticles in the form of uncombined Ag and TiO 2 . The nanoparticles generated had strong antibacterial effects as tested against E. coli. A discussion is given on the role of ultrasonic vibration in the formation of Ag-TiO 2 hybrid nanoparticles by picosecond laser ablation.