Stable steady states of tank reactors belonging to the group of multip
le states are separated by unstable slates. Are separated by unstable
ones. Unstable states, however, do not form the boundary of the region
s of attraction trajectories. It became evident that even for the simp
lest type of the reactor, namely an adiabatic homogeneous tank reactor
, the boundary is given by a certain separating curve. The objective o
f the present study is to determine this separatrix.