A one-dimensional hydrodynamic code, ION, which takes ionization kinetics into account was elaborated and used for the calculation of x-ray emission from plasma produced by the action of a subpicosecond laser pulse onto a solid target in vacuum. Calculated intensities for aluminum target emission are in agreement with experimental and theoretical results of other authors. The simple model gives the correct qualitative description of plasma x-ray emission for the given experimental parameters. The influence of fast electrons on the rate of subpicosecond laser plasma ionization is ascertained. It is shown that x-ray emission intensity depends on laser plasma shape; for the pulse with a more abrupt forward front the intensity is diminished.