The embossing unit includes at least one embossing roller with a rotation axis and a substantially cylindrical surface with a plurality of embossing protuberances with linear extension; a pressure roller with a yielding surface; an embossing nip defined between the pressure roller and the embossing roller; a feed path of a web material extending through said the embossing nip. Along the linear extension thereof the embossing protuberances have a variable inclination with respect to the rotation axis of the embossing roller and a variable cross section along the longitudinal extension of the embossing protuberances.