Disclosed is a process of using a hydroelectric generator adapted to be installed in a water course, having a semi-submerged rotor, including a fixed platform, a rotor means for the conversion of kinetic energy of a fluid in electric energy, having adjusting means to adjust the position of the rotor means. The adjusting means to adjust the position of the rotor means is constrained to the fixed platform and moves, in a controlled way, the rotor means with respect to the fixed platform with at least one degree of freedom, to change at least the orientation of the axis (A) of the rotor with respect to the main flow direction (D) of the water.