Abstract: Apparatus for curing the coating of a workpiece (1), which comprises at least one tank (2) with inert gas heavier than air into which the workpiece (1) is inserted, and at least one UV-radiation source (3) that generates radiation that falls on the workpiece (1) to bring about the curing. The apparatus also comprises an extraction area (4), a recirculation circuit (5) and an insertion area (6), where, respectively, inert gas is extracted from the tank (2), recirculated, and reintroduced into the tank (2). At least one inert gas cooling member (7) is situated in the recirculation circuit (5), thus preventing the inert gas inside the tank (2) from overheating and reducing the risk of instability in the inert gas atmosphere.