The application of temperature responsive hydrogels with ion-exchange domain for nanoscale catalytic reactions is an emerging and attractive area because of the combination of individual unique features: temperature responsive tunability by the polymer domain and the high catalytic reactivity of the nanomaterial. Here, we report the entrapment and/or direct synthesis of reactive Fe and Fe/Pd nanoparticles (about 40-70 nm) in a temperature responsive hydrogel network (N-isopropylacrylamide (NIPAAm), and NIPAAm-PAA). These nanoparticles are stabilized in the hydrogel network and the dechlorination (using trichloroethylene, TCE, as a model compound) reactivity in water is enhanced and controllable in the temperature range of 30-34°C involving polymer domain transitions at lower critical solution temperature (LCST) from hydrophilic to collapsed hydrophobic state. Water fraction modulation of the network and the enhancement of pollutant partitioning by the thermally responsive polymers play an important role in the catalytic activity.