The parametric sensitivity of an industrial autothermal nylon 6 reactor was studied. The sensitivities of the temperature maxima with respect to various parameters of the model are computed numerically. The sensitivity peaks were found to occur (almost) at the same value of the input parameter, thus confirming the generalized nature of the thermal parametric sensitivity criterion. It is shown that this criterion can easily be used to find safer regions of operation of the reactor. The variation of the number-average chain length of the product, mu(nf), with the variation of input parameter, W-0, was also studied. A methodology was suggested to obtain the desired ranges of operation of the reactor which represent an optimal balance between the thermal sensitivity and the sensitivity of mu(nf).