The invention concerns a device for producing thermoplastic containers, in particular bottles, by the blow-moulding or stretch blow-moulding of a pre-heated preform. The device comprises at least one mould consisting of two half-moulds (2) each supported by a mould carrier, the two mould carriers being movable relative to each other. Each half-mould (2) comprises a shell holder (9), supported by the respective mould carrier, and a shell (7) which is equipped with a half-impression (8) of the container to be obtained and can be rendered integral in a detachable manner with its shell holder (9) by rapid-fastening means (19-23). The shell (7) and the shell holder (9) are of complementary shapes such that they contact each other at least partially for heat conduction purposes whilst the pipes and connections for circulating cooling and/or heating fluids are provided in the shell holder alone.