Recent Hubble Space Telescope results on X-ray novae

RXTE has recently discovered two newoptically bright black hole candidates (BHCs): XTE J1859+226 andXTE J1118+480. We observed both with HST/STIS, the firstoutburst observations of X-ray novae with this instrument. We followed broad band spectral evolution, detectedcorrelated X-ray/UV rapid variability and performed high resolution UVspectroscopy. We present a summary ofinitial results on the spectral energy distributions observed