The clinical usefulness of soft denture-lining materials is well established. This laboratory-based comparative study of a heat-processed silicone (Molloplast-B) and a recently introduced fluoroelastomeric soft lining material (Novus) evaluated absorption behaviour in distilled water; the softness of the materials at different thicknesses, both dry and after immersion in water; and their compatibility with denture cleansers. A significant absorption of water, greater than 5% by weight, was displayed by Novus after 4 months’ immersion. The softness of different thicknesses of Novus (up to 1.35 mm) increased significantly upon immersion over the same period when compared to Molloplast-B, which showed no change. Some surface degradation of Novus was evident upon exposure to denture cleansers that was not apparent with Molloplast-B.