The enormous inroads made by renewable energy in recent years have been the key to the development of new technologies designed to obtain energy from a range of resources. Hydrokinetic microturbines used to harness kinetic energy from rivers, tidal and marine currents epitomize such developments. As the reservoir is dispensed with, the water footprint normally associated with conventional hydroelectric generation is minimized. The new prototypes being developed require laboratories with water tunnel infrastructures where they can be accurately reproduced under controlled conditions. However, the construction of a water tunnel demands considerable investment, which prevents many research groups from completing their prototype design work. This paper charts the design of a low-cost hydrodynamic water tunnel at the University of Oviedo, indicating the mechanical and electronic elements as well as the software developments that make up the facility. This construction is a part of a research strategy focused on making the study of new hydrokinetic microturbines designs economically feasible. Moreover, it includes a description of a special software application used to perform the characterization of a hydrokinetic microturbine model in the water tunnel and a demonstration of the scope of the facility in the experimental study of a unit with a Darrieus rotor.