Abstract: A device for spreading a substance onto a moving web of material, which comprises an extrusion head and a rotating bar which is carried by a support member applied to the extrusion head near the outlet of a delivery slit. This latter has an inner profiled recess in which engage limiting blade segments which extend up to the outlet of the delivery slit in order to laterally limit the regions in which spreading is carried out. The rotating bar has its outer surface operatively contacting the web only in the regions in which the substance is spread, and it is recessed or interrupted where no spreading is wanted. This device allows to spread a substance onto a width of web reduced with respect to the width of the extrusion head, or even onto separate strips of the web.