We present and discuss time resolved spectra (KeV range) of solid density plasmas produced by the interaction of clean high intensity laser pulses (400 fs, 0.53 mu m light) with solid and foil targets at intensities between 10(18) W/cm(2) and 10(20) W/cm(2). Results have been obtained with the new PX1 x-ray streak camera which has a temporal resolution of 750 fs in the KeV x-ray range.