This work presents the design and development of a semi-active hybrid orthotic system for support and facilitation of unilateral pathological human walking. The system is based on a novel lower limb orthosis with mechanical control and its combination with non-invasive muscle electrostimulation. The paper presents the concept design and realization of a novel Stance Control Knee Ankle Foot Orthoses (SCKAFO) and the design of Functional Electrical Stimulation (FES) strategies for artificial activation of ankle joint muscles in this hybrid scheme for gait support. In particular, we present the investigation of the effects of electrical stimulation patterns of ankle muscles synchronized in real-time with gait events., on the possible biomechanical alterations to gait in able-bodied individuals (n=8). Bilateral 3D ground reaction forces (GRF) were analyzed between barefoot overground walking with and without FES of ankle muscles. The observed effects of the tested FES strategy are coherent with a physiological gait strategy and compatible with the proposed SCKAFO.