Abstract: The present invention relates to sealing valves used in the petroleum and gas extraction industry, in particular but not exclusively, to medium- or high-pressure ball valves. In particular, the present invention relates to a sealing assembly (101, 102) for ball valves (1), and to a ball valve comprising such an improved sealing assembly. The sealing assembly ensures excellent sealing performance at low and high pressures by exclusively using a thermoplastic material sealing element (31), thus completely eliminating the drawbacks which afflict the sealing system of known type, in particular in relation to the reliability of the sealing elements made of elastomeric material.