Hydrogel nanocomposites have potential applications as functional components of microdevice (e.g. valves, sensors) because they can respond to specific external stimuli. Hydrogel nanocomposites with and without magnetic nanoparticles, were synthesized by UV photopolymerization with various crosslinking densities and magnetic nanoparticle loadings. The hydrogel systems were based on N-isopropylacrylamide as monomer with various crosslinkers like tetraethylene glycol dimethacrylate. Swelling behavior of the gels was analyzed at different temperatures to characterize the effect of crosslinking density and particle loading on swelling transition temperature. The morphology of the nanocomposites was analyzed to characterize the dispersion of magnetic nanoparticles in the hydrogel matrix. Swelling studies were performed to characterize the heating effect of the nanocomposites with response to electromagnetic field. Varying electromagnetic fields were applied to the nanocomposite systems and field impact on swelling properties of the nanocomposites was compared with the thermal response of pure hydrogels. The kinetic studies of the UV photopolymerization reaction were performed with FTIR.