The properties of X-ray Nova XTE J1755–324 , observed with RXTE observatory in 1997 are reported .
The lightcurve of the source was typical for X-ray Novae , except for somewhat shorter decay time scale and the time elapsed between the primary and subsequent secondary and tertiary outbursts .
At the peak of the lightcurve the source had two-component spectrum , typical for the bright X-ray Novae , with a characteristic disk blackbody temperature T _ { in } \sim 0.8 keV and a photon index of the hard power law tail \alpha \sim 2.0 .
The peak luminosity can be roughly estimated as L \sim 10 ^ { 38 } erg/s ( 0.1–100 keV , assuming 8.5 kpc distance ) .
A notable and peculiar feature of the spectral evolution of the source was a short , \sim 10 days long , episode of increased hardness , occurred shortly before the tertiary maximum of the light curve .
During the last RXTE pointed observations \sim 100 days after the primary outburst the source has been found in the hard spectral state with luminosity \sim few \times 10 ^ { 36 } erg/s .
The overall pattern of the temporal and spectral evolution of XTE J1755–324 resembles in general that of “ canonical ” X–ray Novae ( e.g .
Nova Muscae 1991 ) and suggests that the compact object in the binary system is a black hole .