The present Paper describes the implementation of a programme of work, initiated by Electrosila, from the development of experimental two-pole superconducting generators up to 5 MW and 3000 rev min -1, to the manufacturing of a 300 MW prototype superconducting generator which is one of the world's largest of its kind. The experimental superconducting generators have been assembled and tested at Eiectrosila's test rig, The no-load and short circuit characteristics and generator parameters which closely agreed with the calculated values have been determined during the tests. The experimental investigations demonstrated the serviceability of the superconducting generator but they revealed the need for modernization of some parts of the rotor. The experience gained by Electrosila and the extensive theoretical studies made it possible to initiate work on the designing and manufacturing of a 300 MW prototype superconducting generator. This machine, whose major parts have already been manufactured and tested, is intended to optimize the design of future superconducting generators by studying the performance and behaviour under various operating conditions. The main parameters and principles of the generator design are presented in this article. The process of generator manufacture and the complex programme of testing are briefly described.