This paper aims to evaluate the energy and economic performance of IGCC power plants equipped with a syngas storage section. Syngas storage enhances operational flexibility of IGCC power plants as a portion of the produced syngas can be stored during periods of low energy demand and used to increase power output during periods of peaking demand, when the produced electrical energy is most valuable and prices are highest. The results of the study show that IGCC systems with syngas storage require a more powerful prime mover and a larger coal gasification section in comparison to base-load IGCC power plants. In the field of duty-cycles of more likely interest (peaking periods of 2-7 h/day and base/peak power outputs ranging from 0.5 to 0.8), the coal gasification section needs to be enlarged by 5-50% and a fraction from 4% to 30% of the produced syngas needs to be stored. Syngas storage in IGCC power plants leads to a penalty in the overall conversion efficiency (by about 1-6 percentage points in the field of duty-cycles of more practical interest) and higher energy production costs (by about 5-20%) with respect to base-load IGCC power plants. (C) 2013 Elsevier Ltd. All rights reserved.