Recently, the utilization of low-head hydroelectric technologies has received a great attention for the expansion of distributed power systems into isolated regions that are difficult to be connected to the electrical grid, especially in developing countries. The use of gravitational vortex hydropower systems can be a renewable and suitable option to expand electricity access and promote development in these remote regions, which are concomitantly rich in hydric resources, due to this system can operate with low head without the need of a large reservoir and installation area. In this study, the performance of the inlet channel and basin of a gravitational water vortex turbine was investigated. Two inlet channels and two basin geometries were numerically analysed in Ansys Fluent software. The velocity and vortex height were calculated and compared for each setting. It was found that the inlet channel with conical basin tended to produce more symmetric vortex in comparisons with that generated by the cylindrical geometry. Additionally, the conical basin maximized the flow velocity on the water surface area. Key words. Gravitational vortex, low-head hydropower, CFD, cylindrical and conical basin