The two-dimensional Laplace integral transform technique has been applied to get the temperature distributions in the molten and the solid parts of a semi-infinite target irradiated with a pulsed laser. Formulas for the time dependence of the evaporated part and the molten layer thicknesses of the target were found considering the temperature dependence of the absorption coefficient of the irradiated surface as well as the chemical reaction. As the illustrative example computations were carried out on an aluminum target.