Abstract: Method for treating in an enclosure an inner surface of a container made from polymer material, in order to deposit a barrier coating there on, comprises: inserting the container into the enclosure; introducing a precursor gas into the container intended, once transformed into the plasma state, to be deposited at least partially on the inner surface of the container in order to constitute the coating; wherein the method further comprises: transforming the precursor gas into the plasma state by a combination of excitations comprising a main excitation by means of electromagnetic waves comprising microwaves, and a secondary excitation by means of an electrical discharge of alternating voltage having a frequency between 1 kHz and 15 MHz.