We study the minimum-time operation of batch multi-component diafiltration processes. We employ the technique of Pontryagin's minimum principle to derive the candidates for an optimal operation. The optimal operation is defined as a state-feedback strategy. Simulations and numerical optimizations are applied to confirm the optimality of the proposed time-optimal operation. Obtained results are evaluated on two case studies, a typical multi-component diafiltration processes. Standard operational approaches are compared to the optimal operation and the resulting improvements show attractivity of the proposed approach. (C) 2015 Elsevier Ltd. All rights reserved.