By using laser induced thermal desorption (LITD) model, we have calculated spatial distributions of hydrogen deficiency and melting on a H-Si(1 1 1) surface after UV light pulse irradiation. We compared the calculated results with the observed second harmonic response from the Si surface after the UV light pulse irradiation with pulse duration of 30 ps and wavelength of 355 nm. The calculated profiles of hydrogen deficiency reproduced the spatial profiles of the observed SH light intensity from the Si surface very well. The calculated profiles of surface melting were interpreted to be consistent with the spatial profiles of the observed SH light intensity from the bulk Si. Furthermore, the simulation clarified that the hydrogen desorption and the surface melting occur nearly simultaneously. The result also indicated that the surface melting did not give rise to the reduction of pre-exponential factor or activation energy of hydrogen desorption from the H-Si(1 1 1) surface. These results were consistent with the study of the spatially integrated H desorption yield from H-Si(1 1 1) by Koehler and George [B.G. Koehler, S. M. George, Surf. Sci. 248 ( 1991) 158]. (C) 2008 Elsevier B. V. All rights reserved.