A method for producing an absorbent structure for absorbent sanitary articles, comprising the steps of: advancing a first non-woven layer at a first speed, with a first surface of said first non-woven layer facing a suction chamber, distributing superabsorbent granular material on a second surface of said first non-woven layer opposite to said first surface, volumizing said first non-woven layer by means of a toothed portion that penetrates into said first non-woven layer through said second surface and movable with respect to said first non-woven layer with a speed difference.