This article presents a study on the optimal design and operation of a pilot-scale absorber column in post-combustion CO2 capture in the presence of uncertainty. A mechanistic model describing the behaviour of a post-combustion CO2 absorber column is explicitly considered in the present robust optimization formulation. This formulation takes into account process uncertainty, which will impact the absorber column operation due to seasonal or unexpected changes in the operating policies of a fossil-fired power plant, e.g. changes in the flue gas stream. Different scenarios were assessed in order to evaluate the impact of uncertainty on the optimal process design and operation. The results show that environmental constraints determine the impact of process uncertainty in the operation of the absorber column. Similarly, the operation of the absorber unit may become infeasible even when process design specifications are estimated under limited information on process uncertainty. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.