Thermoresponsive inorganic-organic hybrid nanosheets were prepared by surface modification of layered perovskite HLaNb2O7 center dot xH(2)O (HLaNb) with poly(N-isopropylacrylamide) (PNIPAAm) through surface-initiated atom transfer radical polymerization (SI-ATRP). The PNIPAAm-modified HLaNb could be exfoliated into nanosheets, which had a plate-like morphology with a thickness of ca. 25 nm. The aqueous suspension of the PNIPAAm-modified nanosheets in water exhibited phase transitions with increases in temperature to above 34 degrees C. The nanosheets did not form precipitates when dispersed in water, even though the modified polymer chains became hydrophobic at high temperatures.