The overall performance of a "Lab-on-a-Chip" (LOC) design-based mu Direct-Methanol- Fuel-Cell (mu DMFC) are strongly dependent on the gas/liquid phase separation at the anode and cathode side, especially if the mu DMFC is operated transiently with a recovery system for unused fuel. The use of membrane technology enables the separation of the two-phase flow into liquid and gas in a compact and flat device. In general, this is achievable by using a polymeric membrane based micro contactor installed downstream of the mu DMFC. However, polymeric membranes are not methanol resistant in long-term use and have a high transport resistance. In contrast, metallic or ceramic microsieves have a high thermal and chemical stability in methanol as well as a low transport resistance due to their small uniform pore diameters and length. Thus higher separation performance, tailored selectivity and low system energy consumption are possible. In this work, a metallic microsieve based micro contactor for the position-independent gas/liquid phase separation is developed. As a separation layer a nickel microsieve was used with a total thickness of 10 pm. Furthermore, an investigation of the coating process of the microsieves using a-C:H:Si: O, SiO2 and Perfluorodecyltrichlorosilane (PFDTS) is carried out. Additionally, the separation efficiency for different volume flow rates up to 100 nmL/min CO2 are investigated in a new flexible test module to obtain a better insight into the separation process.