Temporal evolution of X-ray spectra of lead plasma produced
by a CO2 laser pulse with energy of 100 J and a duration
of 15 ns has been measured using a six-channel X-ray polychromator.
The polychromator registered the radiation intensity in the
range from 180 to 1850 eV. Plasma temperature was determined
by comparison of measured results with radiation spectra obtained
by numerical simulation. The values of electron temperature
are in good agreement with results of hydro simulations.