  We have mapped four massive cores in Orion using the \ammonia (J,K) = (1,1)
and (J,K) = (2,2) inversion transitions, as part of our effort to study the
pre--protostellar phase of massive star formation. These cores were selected to
be quiescent, i.e. they contain no apparent IR sources and are not associated
with any molecular outflows. These cores are one order of magnitude more
massive than dark cloud cores and have about twice the line width. This paper
focuses on their temperature structure. We find a statistically significant
correlation between the gas kinetic temperature and the gas column density. The
general trend is for the gas to be colder where the column density is higher,
which we interpret to mean that the interiors of these cores are colder than
the regions surrounding them. This is in contrast with dark cloud cores, which
exhibit relatively flat temperature profiles. The temperature gradient within
the massive quiescent Orion cores is consistent with an external radiation
source heating the dust, and dust--gas collisions providing relatively close
coupling between dust and gas temperatures. From linewidth and temperature, we
also obtained the spatial distribution of the turbulence. An anticorrelation is
found between the intensity of emission and the degree of turbulence. Thus, we
suggest that the initial stage of massive pre--protostellar cloud cores is
relatively quiescent condensations which are cooler than their surroundings.
