We present high-speed long term photometric observations from 1992 to 1996 ( UBVRI ) , as well as recently obtained ( 1997 ) spectrophotometric and high resolution spectroscopic studies of the bright galactic supersoft X-ray source RX J0019.8 +2156 .
Our photometry reveals a highly variable object .
The shortest observed quasi-periodic variations are humps with a period of \approx 1.8 h. The timings of the main minimum are not exactly regular and occur on average around phase \phi = 0.0 .
With our new data set we calculated an update of the orbital period .

Our simultaneous spectroscopic and spectrophotometric studies from 1997 give an even more detailed insight : blue and red shifted satellite lines at He ii { \lambda } 4686 and at the strong Balmer lines , which are interpreted as high velocity outflows , can clearly be detected .
We also present for the first time an analysis of this supersoft source by means of Doppler tomography .
The lines of He ii ( \lambda \lambda 4542 , 4686 ) , H _ { \alpha } and H _ { \beta } show no emission from an accretion disk .
These emission lines originate in regions within the binary system with very low velocities .
The spatial origin of the emitting material is not quite clear and will be investigated in a follow-up paper .