As shown by Luus et al. (1992), determination of the optimum catalyst blend along a tubular reactor to maximize the yield of a particular component is a difficult problem due to the large number of local optima. By using iterative dynamic programming, the effects of the region reduction factor and the choice of the initial region size are analyzed in detail for this problem. Even if a single grid-point for the state is used, the likelihood of obtaining the global optimum is very high if the initial region size is chosen to be sufficiently large.