Pd-Ag membranes are well-proven technologies in nuclear fusion fuel cycles especially for what concerns the Q2 (Q = H, D, T) recovery from the tokamak exhaust gas stream. Due to their ability in separating Q2 from other gaseous species, they are also proposed to be implemented in the tritium extraction and recovery system of the DEMO helium cooled pebble bed (HCPB) blanket. Inside the HCPB, the produced tritium is recovered by purging with a large He flow doped with H2 (0.1%wt). Thus the gas stream leaving the blanket will contain a very low Q2 and Q2O concentration diluted in a large amount of He. The paper presents the design and the first experimental results of a new facility, named MeSMeR, erected at ENEA Frascati. The facility hosts a multi-tube module made of 10 Pd-Ag tubes (total surface area of 0.16 m2 and average thickness of 116 μm). The membrane module has been assembled by using a modified tube connection. The aim is to assess the Q2 permeation efficiency of the membrane module under several operating conditions and, particularly, by varying the He/H2 feeding ratio and the total feed flow rate.