In the present study, a new lattice thermal conductivity model for a thin-film semiconductor is proposed. This model is considered, compared to the existing models, to be more mathematically consistent in the sense that the heat flow is contributed solely by the low-dimensional phonons, and the spatial confinement effects not only on the phonon group and phase velocities but also on the Debye temperature are taken into consideration. To count the boundary scattering effect, an analytical or empirical boundary scattering rate is suggested and added to the total scattering rate via the Mattiessen's rule. It is found this newly proposed model predicts as well as the existing models and reasonably well with the experimental data. (c) 2006 Elsevier Ltd. All rights reserved.