Kappa-carrageenan/polyvinyl alcohol cross-linked hydrogels was formulated using genipin as a natural and nontoxic cross-linker to achieve a controlled drug release. beta-Carotene was immobilized and the release study was evaluated under in vitro conditions. Monitoring beta-carotene release was carried out by structure modification using cross-linker and minimization of burst release. It was found that using genipin can stop burst release in the hydrogels and control active material better than native films as a result of structural modification. This suggests that the burst release is depended highly on the degree of cross-linking and the mesh space available for drug diffusion. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are carried out to study the characteristics changes of native and cross:linked hydrogels. Also, field emission scanning electron microscope (FESEM) was performed to study microstructure of hydrogels. The transport mechanism seems to be determined by the strength of the gel network due to genipin concentration changes. Finally, diffusion coefficient is determined for native and cross-linked hydrogel. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.