  A full-sky template map of the Galactic free-free foreground emission
component is increasingly important for high sensitivity CMB experiments. We
use the recently published \ha data of both the northern and southern skies as
the basis for such a template.
  The first step is to correct the \ha maps for dust absorption using the 100
$\mu$m dust maps of Schlegel, Finkbeiner & Davis (1998). We show that for a
range of longitudes, the Galactic latitude distribution of absorption suggests
that it is 33 per cent of the full extragalactic absorption. A reliable
absorption-corrected \ha map can be produced for $\sim 95$ per cent of the sky;
the area for which a template cannot be recovered is the Galactic plane area
$|b| < 5^{\circ}$, $l=260^{\circ}-0^{\circ}-160^{\circ}$ and some isolated
dense dust clouds at intermediate latitudes.
  The second step is to convert the dust-corrected \ha data into a predicted
radio surface brightness. The free-free emission formula is revised to give an
accurate expression (1 per cent) for the radio emission covering the frequency
range 100 MHz to 100 GHz and the electron temperature range 3000 to 20000 K.
The main uncertainty when applying this expression is the variation of electron
temperature across the sky. The emission formula is verified in several
extended H{\sc ii} regions using data in the range 408 to 2326 MHz.
  A full-sky free-free template map is presented at 30 GHz; the scaling to
other frequencies is given. The Haslam et al. all-sky 408 MHz map of the sky
can be corrected for this free-free component, which amounts to a $\approx 6$
per cent correction at intermediate and high latitudes....
