Ward et al. (Ward, J. D.; Mellichainp, D. A.; Doherty, A F. Ind. Eng. Chem. Res. 2004, 43, 3957) investigated the effect of process chemistry on the selection of the operating policy for plants with recycle. This paper extends that work to consider the possibility of reactor temperature as a degree of freedom in plantwide process operation. It is possible to predict, based on the process chemistry, when it may be appropriate to implement a variable-temperature operating policy, and, alternatively, when a constant-temperature operating policy is appropriate in the face of a production rate change or other disturbances. An interesting and nonobvious result is also developed: For so-called bounded chemistries, it is usually optimal to operate the process with the reactor at its high-temperature constraint, even if the activation energy of the undesired reaction is greater than the activation energy of the desired reaction. This means that the plantwide operating policy is the same for almost all bounded chemistries. In contrast, for nonbounded chemistries, the operating policy follows conventional wisdom and changes depending on the relative magnitude of the activation energies. Implications of the optimization analysis for control structure design are also discussed.