Batch processes are usually complex and highly nonlinear systems. Modeling error can be the cause of bad performance when optimal input profiles computed for a particular model are applied to the actual plant. The approach followed in this paper uses the available model and actual plant measurements to modify the operation of the next batch, without requiring the remodeling of the process. The effect of model error on the convergence of the iterative batch to batch input profile determination is investigated. The method is applied through computer simulations to the determination of the optimal feedrate profile for a cell mass production process. A model parameter update scheme is also proposed, based on the convergence analysis. This is applied to the determination of the optimal temperature profile of bulk polymerication of the optimal temperature profile of styrene.