Operability analysis is one of the bridges that links process design and control. In this paper, we analyze the steady-state operability characteristics of classical reactors (CSTR and PER) in the framework of Vinson and Georgakis (DYCOPS-5. Fifth IFAC Symposium on Dynamics and Control of Process Systems. 1998, pp. 700-709, J, Proc. Control 10 (2000) 185). Reaction schemes vary from simple first-order A --> B to industrially relevant competing reactions. The nonlinear nature of reactors requires the use of special computational techniques for the determination of the operability index (OI). This study clearly brings out the potential of the OI framework. In addition to measuring the servo, regulatory, and overall operability of the systems studied. we were able to identify safe operating regions and tolerable disturbances with the available inputs. This analysis also points to optimized process conditions.