A hybrid process for the capture of C O2 and H2 from a treated fuel gas mixture is presented. It consists of two hydrate crystallization stages operating at 273.7 K and 3.8 and 3.5 MPa, respectively. The C O2 -lean stream from the first stage is directed to a membrane separation unit whereas the C O2 -rich one is directed to the second hydrate stage. These operating pressures at the crystallization stages are possible by adding 2.5% by mole propane. Propane enables the reduction in the hydrate formation pressure and thus reduces the cost associated with the compression of the fuel gas. The two hydrate stages would operate at 7.5 and 3.5 MPa without adding propane. This work provides the relevant kinetic data, as well as the separation efficiency and recoveries achieved. © 2009 ASCE.