N-isopropylacrylamide (NIPA)/N-tert-butylacrylamide (NTBA) and NIPA/N, N-dimethylacrylamide (NDMA) submicron-sized copolymer gel particles of various compositions were prepared by precipitation polymerization and their swelling behaviours were studied with different compositions and temperature using photon correlation spectroscopy. The experimental data showed that the volume transition temperature (T-v) of NIPA/NTBA copolymer gel decreased with increasing mole ratio of NTBA, while T-v of NIPA/NDMA copolymer gel increased with the mole ratio of NDMA.