The design of an energy efficient CO2 capture unit is of great importance for the deployment of Carbon Capture and Storage (CCS) technologies at industrial scale and more specifically for post-combustion framework. In that case, both CO2 capture ratio and CO2 purity should be high enough (typically above 90%) [1]. Today, the best currently available technology is absorption in a chemical solvent (such as monoethanolamine, MEA) and is considered as a reference for post combustion capture. The corresponding energy requirement is of approximately 4GJth (thermal basis)/ton of recovered CO2 (including compression requirement). A target of 2 GJth/ton is often mentioned according to the European Union recommendations [2]. Membrane processes have shown growing interest as an alternative to this reference technology. However they remain energy intensive when both high CO2 purity and capture ratio are imposed and when diluted CO2 flue gas are to be treated [3]. Consequently, for diluted CO2 flue gases containing 5 % and 15% CO2, typical of a natural gas turbine flue gas and coal combustion respectively, a multi-stage membrane processes or hybrid systems are needed to achieve the capture targets [4,5]. However, design studies on hybrid processes based on a membrane unit for carbon capture are scarce [6]. In this work, two hybrid processes are investigated (through simulation) for CO2 capture on natural gas turbine and coal power plant respectively: (i) A hybrid process combining flue gas recycling, combustion in oxygen enhanced air (OEA) and CO2 capture by membranes (ii) A hybrid membrane / cryogenic separation based on a first step CO2 pre-concentration with a membrane unit and a second step CO2 cryogenic condensation. For each hybrid process, a parametric analysis has been performed regarding the process parameters and the membrane CO2 /N2 selectivity, covering current and prospective material development. Finally, the optimal operating conditions are identified and the potential improvement of the overall efficiency is discussed.