This paper studies the condition for criticality and some related problems for the stationary-state of the continuous-flow stirred tank reactor(CSTR) under non-adiabatic operation with heat loss through its wall. Dimension-Jess parameters may be used in analysing the thermally sensitive region in order to reduce the problem to the same form as that for the simpler adi-abatic CSTR. Mathematical expressions for the two important thermally sensitive boundaries of ignition and extinction are derived. And it is also shown that when the thermally sensitive regions disappear. Because the left-hand side of the above relation contains parameters that are easily controlled

this relation possesses practical importance in chemical engineering design and control.