Interaction of nanosecond pulsed lasers with material was studied from thermal point of view using experimental techniques and theoretical approach of dimensional analysis. Experimental data of laser heating, melting and plasma formation on metallic samples and silicon, presented mainly in previous publication and partly in this paper, were used for formation of experimental mathematical model in the form of criteria equations of laser-material interaction process. Four different criteria equations were created: for maximum surface temperature increase, melting threshold, melting duration and plasma formation threshold. Two equations account for changes of thermal properties with temperature. The value of latent heat of fusion was found to have almost no influence on melting duration. The presented model showed good agreement with the measured results. The criteria equations can be used for approximate prediction of laser pulse effects on materials without creating an exact mathematical or numerical model and for control of technological processes. (c) 2006 Elsevier B.V. All rights reserved.