The growing interest on low-carbon energy systems has been essential to develop new electricity devices based on renewable resources. In this context, channel turbines are an excellent alternative to supply demands that are isolated from power mains. These devices, which harness the kinetic term of the water current, can be installed in hydraulic channels, rivers, or estuaries. This article carries out an experimental characterization of a hydrokinetic turbine in a hydrodynamic water tunnel under low velocity conditions, so its behavior under open field conditions can be obtained. The results show the relevance of the blockage effect made by the turbine during the power stage. Keywords: hydrokinetic turbines, blockage, water channels, low velocity