The invention relates to a hydroelectric machine. According to the invention, the machine comprises at least one arm (5) which can rotate around an axle (4), said axle (4) having a base (3) which is disposed at the centre of a circular tank (2) that is filled with water. Moreover, the aforementioned arm rests on the circular track (16) which is formed by the upper surface of the external wall (2A) of said tank (2), by means of non-deforming wheels (15). Furthermore, said arm (5) supports an assembly comprising a pump (9) and, downstream, a turbine (11) which is connected to the rotor of a first electric current generator (12). In addition, the above-mentioned arm (5) is solidly connected to a first sheave wheel (14) which is in turn connected to a second sheave wheel (18) by means of a transmission belt (17), the axle (19) of said second sheave wheel (18) being solidly connected to the rotor of a second electric current generator (20).