A study has been conducted to evaluate the feasibility of installing an ECRH system on the JET tokamak. This paper presents an overview of the studies performed in this framework by an EU-Russia project team. The motivations for this major upgrade of the JET heating systems and the required functions are discussed. The main results of the study are summarised. The usefulness of an EC system for JET is definitely confirmed by the physics studies. No strong limitations for any of the functions envisaged have been found. This has led to a preliminary conceptual design of the system.