Mathematical modelling and simulation of a styrene plant was made for the synthesis of a regulatory control structure for the purpose of replacing the existing one. The structural model was constructed considering the differential and algebraic relations describing the process. Utilizing the structural model, alternative feasible control structures were determined by integer linear programming (ILP) techniques developed in this study. The ILP formulations developed were proved to be very efficient in generating structurally controllable alternative feasible control configurations. The performances of the alternative structures were evaluated by utilizing the gain information obtained by steady-state modelling and using the interaction criteria RGA, NI, SVD, IMCIM and RDG. Thus, a systematic procedure for synthesizing regulatory control structures for a large-scale process is established by utilizing ILP1 and ILP2 formulations which are the modified versions of the MILP formulations proposed by Georgiou and Floudas (81st AIChE Annual Meeting 1989). The necessary improvements in MILP formulations were made in order to make them applicable for a large-scale system.