A series of intercalated and exfoliated nanocomposites montmorillonite-ulvan was prepared. Ulvan, extracted from the green algae, is a water-soluble polysaccharide biopolymer. Depending on the drying process, air or freeze drying, ulvan were inserted in the interlayer space or adsorbed on the both sides of inorganic layers. The crystallization of water molecules bounded to the ulvan induced the delamination of the layers during the lyophilization. Thermogravimetric experiments show a high percentage (approximately 51%) of organic matter for the freeze dried samples and a lowest one (approximately 17%) for the air dried solids. X-Ray Diffraction patterns exhibit a d(001) varying with the content of organic matter. When the delamination occurs, the (001) reflection disappears. Transmission electron microscopy micrographs show individual layers for the highest amount of ulvan.