In this paper, the authors have designed local internal model controllers on the basis of multiple-linear discrete transfer function models and the weighted sum of the output from the local internal model controllers (Non-linear Internal Model Controller) has been used to control the nonlinear process. The effectiveness of the proposed control schemes has been demonstrated on a pH process. From the extensive simulation studies, we have shown that the proposed non-linear internal model controller provides satisfactory servo as well as regulatory performances. © 2011 Zhejiang University.