To increase the barrier effect of a metallized film intended for use I the packaging, in particular of food products, a particular composition of the plastic layer (A) is suggested, on which the metal layer (M) is deposited by vacuum evaporation. The plastic layer comprises a polypropylene and butene copolymer and is subjected to a preliminary surface activation treatment, preferably to a flame treatment, and to a subsequent plasma treatment under partial vacuum conditions prior to metallization.