This paper reviews recent contributions to the area of optimization of polymerization reactor operation and demonstrates the applicability of the optimization package OPTPAC developed by Tieu (1991) in solving optimization problems. OPTPAC is a PC-based software package designed to assist the user with limited knowledge in optimal control to tackle dynamic optimization problems with smooth and continuous profiles. The surveyed papers cover batch, semi-batch and continuous reactors. Five case studies - two to investigate the effects of adding a penalty function on the polydispersity index of the objective function and three to compare the results obtained by OPTPAC with those reported in the literature (O＇Driscoll and co-workers, 1989,1990) - are presented in this paper. The polydispersity index decreased at the expense of increasing batch time when a penalty function was added to the objective function of the minimum end time problem. For the comparative examples, OPTPAC gave improved results as compared to those reported in the literature.