ABSTRACTToday polysaccharide based hydrogel nanocomposites are receiving high importance as biomaterials for drug delivery. Inorganic nanoparticles (NPs) are incorporated into the polymer matrix to provide novel functionalities to the hydrogels. However, the effect of nanofillers on the release properties has not been totally understood. In this work, we investigate the influence of inorganic functional nanofillers (Fe₃O₄ and Au NPs) with variable size and shape on the structure of κ-carrageenan hydrogels and on the kinetics and release mechanism of methylene blue (MB) as model drug. It was shown that, depending on the nature of the nanofiller incorporated, and for equivalent nanofiller content, the mechanism of MB release can be adjusted either to by diffusion or polymer relaxation mechanism. The mechanism of the MB release was found to be determined by the strength and microstructure of the gel network and extent of gel swelling, which are affected by the extent of incorporation of the nanofillers.