Abstract: This invention relates to the preform to produce a plastic container for packaging foodstuffs, and especially to blow mould thin-walled containers which can be hermetically closed with a metal lid by double seaming. The preform (1) includes a body (4) and a convex hemispherical bottom (6). The body (4) has a conical shape that flares towards a cylindrical neck (2) surrounded by a flange (3) that terminates in a thickened rim (5). Preferably, the angle (?) at which the internal body surface (4) flares towards the cylindrical neck is greater than the angle (?) at which the external body surface (4) opens upwards, and the thickness (g2) of the cylindrical neck (2) is less than the thickness (g3) of the bottom (6).