This paper describes numerical simulations of the radiative properties of a laser ablation plume of lithium expanding into vacuum. In this model, the transport of matter is obtained from the solutions of the gas dynamic equations in the isothermal or adiabatic flow regimes, respectively. From these solutions, plume regions are identified where local thermodynamic equilibrium (LTE) is satisfied using initial conditions relevant to the pulsed laser deposition (PLD) of materials. The total emission and absorption coefficients of the plume are obtained and the corresponding equation of radiative transfer is numerically integrated in a direction perpendicular to the expansion axis to generate synthetic "side-on" spectra. The usefulness of the model for the interpretation of time- and space-resolved spectra or fast imaging data of laser ablation plumes is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.