  The properties of the deconfined phase of ${\cal N}=1$ supersymmetric
Yang-Mills theory in $(3+1)$-dimensions are studied within a $\cal T$-matrix
formulation of statistical mechanics in which the medium under study is seen as
a gas of quasigluons and quasigluinos interacting nonperturbatively. Emphasis
is put on the temperature range (1-5)~$T_c$, where the interaction are expected
to be strong enough to generate bound states. Binary bound states of gluons and
gluinos are indeed found to be bound up to 1.4 $T_c$ for any gauge group. The
equation of state is given for SU($N$) and $G_2$; it is found to be nearly
independent of the gauge group and very close to that of non-supersymmetric
Yang-Mills when normalized to the Stefan-Boltzmann pressure and expressed as a
function of $T/T_c$. Finally the orientifold equivalence is shown to hold at
the level of the equation of state and its accuracy at $N=3$ is shown to be
very good.
