A modular heat-exchange system, includes a plurality of heat exchanger modules, each of which includes a plate provided with internal conduits for the passage of a conditioning fluid. The conduits contain openings on connecting sides of the plate and locking arrangement for connecting two adjacent heat exchanger modules in an assembly. A connecting arrangement is provided for sealingly connecting the openings of the two adjacent heat exchanger modules. Each heat exchanger module includes on each connecting side a seat containing at least one of the openings and configured so as to form with a similar seat of an adjacent heat exchanger module a housing that is open and arranged for receiving the locking arrangement and the connecting arrangement.