  A nearly simultaneous X-ray/optical (Chandra and VLT) observational campaign
of RX J0806.3+1527 has been carried out during November 2001. These
observations allowed us to phase the X-ray and optical light curves for the
first time. We measured a phase-shift of about 0.5, in good agreement with the
presence of two distinct emission regions and with the X-ray irradiation
process predictions. The Chandra data allowed us also to study in details the
X-ray spectrum of RX J0806.3+1527, which is consistent with a soft (kT<70 eV)
and small (R_BB<20 km) blackbody component. We discuss the present findings on
the light of the models proposed so far to account for the X-ray emission
detected from RX J0806.3+1527, and its twin source RX J1914.4+2456.
