Method for forming a container for food products starting from a preform (10) made of plastic material, said preform (10) comprising an opening (11) and a bottom (12) opposite to the opening (11), the method comprising the steps of:-introducing into the preform an agent (15) intended to perform a sterilising action, said agent (15) if treated with microwaves being heated up more quickly than the material of the preform (10)-directing the microwaves towards the preform (10).The step of introducing said agent (15) takes place before directing the microwaves towards the preform (10) and envisages collecting said agent (15) on the bottom (12) of the preform (10) the step of directing the microwaves towards the preform (10) envisages the evaporation of the agent (15) and the condensation thereof in contact with the preform (10) the step of directing the microwaves towards the preform (10) further envisaging the re-evaporation of the agent (15) condensed on the preform (10) and the subsequent softening of the preform (10) itself for its shaping.
