Theoretical investigations and estimations of threshold laser intensities for melting and evaporation of a small metal (solid) spherical and spheroidal particle placed in a liquid or gaseous medium by short laser pulses are carried out. The time dependencies of nanoparticle temperature are used for estimations of threshold laser intensities and their dependencies on pulse duration and radius of particles are discussed. Comparison of some predicted values of the threshold laser intensities for melting and evaporation of gold spherical nanoparticle in liquid media with experimental data is given and agreement of theoretical results with experimental data validates the model developed. These results can be used in the processes of treatment of nanoparticles in laser technologies. (c) 2006 Elsevier B.V. All rights reserved.