  We study the thermodynamics of de Sitter black holes with a conformally
coupled scalar field. The geometry is that of the ``lukewarm''
Reissner-Nordstrom-de Sitter black holes, with the event and cosmological
horizons at the same temperature. This means that the region between the event
and cosmological horizons can form a regular Euclidean instanton. The entropy
is modified by the non-minimal coupling of the scalar field to the geometry,
but can still be derived from the Euclidean action, provided suitable
modifications are made to deal with the electrically charged case. We use the
first law as derived from the isolated horizons formalism to compute the local
horizon energies for the event and cosmological horizons.
