The invention relates to a process for post-preparation labelling of liposomal formulations with F (fluorine) isotope, wherein a) during the preparation of the liposomal formulation, a phospholipid derivative modified by terminal alkyne functional group(s) is incorporated into the membrane of the liposome, then b) the alkyne groups of the liposomes obtained in step a) are reacted with an 18F-labelled azide derivative. Further subjects of the invention are the labelled liposomes prepared by the process, and the liposomes for diagnostic application. The new intermediates used in the process of the invention form a subject of the invention as well.
