Abstract: Cooling by carbon dioxide. The apparatus comprises:as an expansion member, at least one appliance (5) for the expansion and separation of the solid and gaseous phases, which is interposed between the pipe (3) and the chamber (4) and which has a gaseous-phase outlet and a solid-phase outlet communicating with the chamber via a sealing means (10),a gaseous-phase recovery pipeline (15) connected to the gaseous-phase outlet of the appliance (5),a compressor (16) fed by the recovery pipeline (15),and a means (17) for liquefying the gaseous phase for the purpose of re-using it.Application for the deep-freezing of food products.