Apparatus for the formation of gussets to be applied in the crotch region of pantyhose articles upon the assembly thereof on a machine having a plurality of shapes (2) over which the stockings to be assembled to form pantyhose articles are fitted in pairs, the gussets being formed out of a ribbon (30), coming from a relevant input section (I), by means of a cutter (4) located downstream of said section (I), characterized in that it comprises a first plane (7) upstream of the cutting unit (4), a second and a third planes (8,9) each of which is apt to engage a corresponding side of the ribbon (30), said second plane (8) being movable from and to the ribbon (30)-inputting section (I) and said third plane (9), located downstreaam of the cutting unit (4), being movable between a position in which it results in face-to-face relationship with the second plane (8) and a position in which it engages the individual gussets (66) already formed, in an arrangement suitable for the transfer thereof to the crotch region of the pantyhose article (Fig. 1).