The interfacing of a on-chip microreactor with the external world is investigated from the microfluidic point of view. A method for coupling of input and output capillaries perpendicular on the micro-reactor plane is presented. The micro-reactor consists of a planar array of metallic electrodes covered by a borofloat® glass reservoir provided with openings for the input and output capillaries having and internal diameter in the range of 220 – 500 µm on a chip of . The reservoir has a volume of 60 µl and was manufactured by means of wet etching using a lithographically patterned mask. The capillaries are vertically inserted in the reservoir’s openings and leaned by means of silicone rings with cylindrical and respectively conical shape, the larger of them being glued with a silicone based adhesive. The key process steps were: cutting the rings with appropriate shape, size and contact surface; aligning …