AbstractAfter a brief survey of the different alternatives considered for the design of RFX, this paper describes the technical aspects of the plant components and their function in the system. The final work of the project started in 1984 and construction was concluded in 1991. The RFX experiment started with the commissioning operations, without plasma, realised in three different phases in 1991, and plasma experiments started in November 1991. The immediately subsequent experiments were aimed at setting-up and studying the RFP configuration at low plasma current (up to 0.5 MA).