Muscle selectivity during sFES in upper limb is an issue because of the presence of the “overflow” phenomenon. Surface electrodes array can augment muscle selectivity by generating an irregular electric field under their surface. A study on a) the influence of the anode electrode position factor and b) the impedance of the hydrogel membrane of the electrode array factor to muscle selectivity was made. A platform consisted of a garment with incorporated kinematic sensors and a multi-channel sFES system with an electrode array was used. We concluded that muscle selectivity is correlated to the anode position and the impedance of the hydrogel membrane.