  Based on observations with the X-ray observatories Chandra and XMM-Newton we
present results from a detailed spectro-imaging and timing analysis of the
central compact X-ray source RX J0822-4300 in the supernova remnant Puppis-A.
The superior angular resolution of Chandra allows for the first time to
pinpoint the point source nature of this object down to $0.59\pm0.01$ arcsec
(FWHM) and to determine its position:{RA=$08^{\rm h}21^{\rm m}57.40^{\rm s}$,
Dec=$-43^{\circ}00^{'}16.69^{''}$ (J2000)} with sub-arcsecond accuracy.
Spectral fits based on Chandra and XMM-Newton data provide a tight constraint
on the emission properties of RX J0822-4300. Most of its X-ray emission seems
to be of thermal origin. A model spectrum consisting of two blackbody
components with $T_{1}\simeq 2.6\times10^{6}$ K, $T_{2}\simeq 5.0\times10^{6}$
K and $R_{1}\simeq 3.3$ km, $R_2 \simeq 0.75$ km for the blackbody temperatures
and the size of the projected emitting regions, respectively, provides the best
model description of its spectrum. A search for X-ray pulsations from RX
J0822-4300, revealed an interesting periodicity candidate which, if confirmed,
does not support a scenario of steady spin-down.
