  The X-ray binary XTE J1817-330 was discovered in outburst on 26 January 2006
with RXTE/ASM. One year later, another X-ray transient discovered in 1996, XTE
J1856+053, was detected by RXTE during a new outburst on 28 February 2007. We
triggered XMM-Newton target of opportunity observations on these two objects to
constrain their parameters and search for a stellar black holes. We summarize
the properties of these two X-ray transients and show that the soft X-ray
spectra indicate indeed the presence of an accreting stellar black hole in each
of the two systems.
