The formation of Ti, Si, Ag and Au nanoparticles under laser ablation of metal targets in liquid environment (H2O, C2H5OH, C2H4Cl2) is reported. The use of a high-repetition-rate Cu vapor laser (wavelength 510.5 nm, pulse duration 20 ns, repetition rate 15 kHz) allows high rate of nanoparticles formation as a sol. The nanoparticles are characterized by X-ray diffraction (XRD), UV-visible transmission spectrometry. high resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM). The nanoparticle size dependence on both the laser fluence and the nature of the liquid is studied. In some cases, nanoparticles of compounds are formed via reaction of the metal with the liquid. (C) 2002 Elsevier Science B.V. All rights reserved.