• Integration of membrane technology for decarbonization of gasification power plants. • Techno-economic and environmental assessment of decarbonized gasification plants. • Membrane-based CO 2 capture system increases the overall plant energy efficiency. • Membrane reduces capital cost (9%), operational cost (10%) and electricity cost (7%). • Decarbonized gasification plants are economic viable for current 75 €/t carbon tax. Membrane technology is one promising technology for CO 2 capture from industrial gases. The application of membrane system in gasification-based power plants is particularly appealing considering the elevated pressure of syngas subject to decarbonization resulting in lower energy and economic penalties for CO 2 capture. As key novelty element of this work, the membrane technology was evaluated in both alone and hybrid configuration with gas-liquid absorption in view of decarbonization of Integrated Gasification Combined Cycle power plants. Assessed decarbonized gasification-based power plant concepts produce about 450 MW net output with 90% CO 2 capture rate. An integrated techno-economic and environmental evaluation methodology (based on modelling, simulation and process integration) was applied to quantify the most important plant performance indicators. For comparison, similar IGCC designs without decarbonization feature or with decarbonization by chemical and physical gas-liquid absorption were also analysed. The overall conclusion is that the membrane technology has important techno-economic benefits in comparison to chemical and physical absorption e.g. greater overall net energy efficiency (up to about one net percentage point), lower specific capital investment costs (down to 9%), lower operational & maintenance costs (down to 10%), lower electricity production costs (down to 7%), lower CO 2 capture costs (down to 50%).