In order to study ultrashort laser-produced plasmas, we developped at INRS a subpicosecond x-ray streak camera, called the PX1. The PX1 has been completely characterized.' Using an extraction field of 250 kV/cm, a record 350 fs temporal resolution has been measured with x-ray pulses in the KeV range. Also, we obtained a 40 tim spatial resolution along the 15 mm slit of the photocathode in single-shot. The PX1 has also been used in accumulation mode and a temporal resolution of 800 fs has been obtained with unlimited dynamic range. Recently, in an effort to improve upon these results, a new x-ray streak camera has been developped and tested. This camera, called the FX, uses the new generation of bilamellar tube technology. This includes a better control of the paraxial trajectories, a larger quadripolar lense to increase the usable width of the photocathode and a new design of the electronic lenses to permit the use of higher voltages.