The invention concerns a condenser consisting of stacked plates (2) provided each with a raised peripheral edge (3) in sealed assembly to define flow channels between the plates for a refrigerating fluid (F1) and a cooling fluid (F2). The plates comprise communicating passageways (124) for the passage of the refrigerating fluid and the cooling fluid from one flow channel to the other. Annular ducts (122) are provided opposite the communicating passageways to prevent the fluids from being mixed. A bottle (100) is interposed between a cooling section (94) and sub-cooling section (96). The invention is applicable to motor vehicles.