In the actual context of Swiss nuclear phase-out stategy, harvesting the extensive potential of small hydropower (<10MW), in particular on existing infrastructure, is a priority. In this framework, a new kinetic turbine has been jointly developed between the HES-SO Valais/Wallis and Stahleinbau Gmbh in SwitzerlandIn the actual context of Swiss nuclear phase-out strategy, harvesting the extensive potential of small hydropower (<10MW), in particular on existing infrastructure, is a priority. In this framework, a new kinetic turbine has been jointly developed between the HES-SO Valais//Wallis and Stahleinbau Gmbh in Switzerland, to harvest the kinetic energy of free surface flows in existing facilities such as run-of-river tailrace channels, headrace tunnels or water treatment stations. The hydraulic design of the ducted turbine has been obtained by flow numerical simulations. The objective of the present research project is to build a first prototype of 1 kW as well as an open-air platform and to test it in a tailrace channel. The chosen pilot site is the Lavey run-of-river hydropower plant’s tailrace channel, installed in the Western side of Switzerland on the Rhône River. The final purpose is to confirm the hydraulic efficiency results obtained by simulation and the electro-mechanical concept in view of a product industrialization phase to tap this potential in Switzerland and elsewhere. The global concept of the variable speed prototype, including the actual hydraulic and mechanical design, the electrical generator and the driving electronics as well as the integrated instrumentation are first presented. The specially designed open-air testing platform to test the turbine in the channel is also introduced. Finally, the efficiency of the turbine is optimized using steady pressurized numerical simulations and assessed in case of unsteady homogeneous multiphase turbulent simulations in the tailrace channel of Lavey. A power coefficient higher than 80% is reached.