  We report on a 30ksec XMM-Newton observation of the central region of the Cha
I star forming cloud. Virtually all known T Tauri star members and most of the
very-low mass objects including two bona-fide brown dwarfs (spectral types M7.5
and M8) are detected. We identify several new candidate members in the X-ray
image. Spectral analysis of the X-ray bright stars shows that previous X-ray
studies in Cha I have underestimated the X-ray luminosities, as a result of
simplified assumptions on the spectral shape. No dramatic changes in the
correlations of X-ray luminosity with age, effective temperature and mass are
seen at the substellar boundary, and the lowest-mass objects behave similar to
the higher-mass T Tauri stars in terms of variability. Thus the same dynamo
mechanism seems to operate in both low-mass stars and brown dwarfs, at least at
young ages. On the other hand, the only two A-type stars in the field show very
different X-ray properties, suggesting that various emission mechanisms may be
at work in intermediate-mass stars.
