  We present observations of a sample of optically-faint, hard X-ray sources of
the kind likely to be responsible for much of the hard X-ray background. We
confirm that such sources are easily detected in the near-infrared, and find
that they have a featureless continuum suggesting that the active nucleus is
heavily obscured. The infrared colours of the majority of the targets observed
are consistent with absorbed elliptical host galaxies at z=1-2. It is likely
that we are observing some of the brighter members of the important new class
of X-ray Type II quasars.
