A device (10) for thermally treating packaged goods by means of a hot air or gas stream (28), particularly for the shrink treatment of film-wrapped goods, such as packs or the like, is disclosed. The device includes a hot gas generator (12) having a gas burner (14) whose combustion products (16) pass into a mixing device (18) via at least one supply opening (38). The mixing device (18) is formed by a channel portion (20) arranged between a conduit portion (22) formed as an inflow area (23) and an outflow area (25), wherein the mixing device (18) comprises at least one opening (32) for supplying the combustion products (16) and for mixing them with the gas stream (26) of the channel portion (20).