The CO2-capture performance of microporous coordination polymers of the M/DOBDC series (where M = Zn, Ni, Co, and Mg; DOBDC = 2,5-dioxidobenzene-1,4-dicarboxylate) was evaluated under flow-through conditions with dry surrogate flue gas (S/1 N-2/CO2). The CO2 capacities were found to track with static CO2 sorption capacities at room temperature, with Mg/DOBDC demonstrating an exceptional capacity for CO2 (23.6 wt %). The effect of humidity on the performance of Mg/DOBDC investigated was by collecting N-2/CO2/H2O breakthrough curves at 70% RH and subsequent thermal regeneration, only about 16% of the initial CO2 capacity of Mg/DOBDC was recovered. However, in the case of Ni/DOBDC and Co/DOBDC, approximately 60 and 85%, respectively, of the initial capacities were recovered after the same treatment. These data indicate that although Mg/DOBDC has the highest capacity for CO2, under the conditions used in this study, Co/DOBDC may be a more desirable material for deployment in CO2 capture systems because of the added costs associated with flue gas dehumidification.