Macroporous temperature-sensitive poly-(N-isopropylacrylamide) (PNIPA) hydrogels were prepared by a novel phase-separation technique to improve the response properties. In comparison with a conventional PNIPA hydrogel-prepared in water, these macroporous hydrogels, have prepared by polymerization in aqueous sucrose solutions, have higher swelling ratios at temperatures below the lower critical solution temperature and exhibit much faster response rates to temperature changes.