Poly(divinylsiloxyethylene glycol), which consists of alternating oligo(ethylene glycol)s (MW = 300) and divinylsiloxanes were prepared by a polycondensation reaction (M-n = 6500-9300, M-w/M-n = 2.01-2.27). The obtained polymer (PVSE300) showed a lower critical solution temperature (LCST) at 10.5 degrees C, meaning that the polymer was soluble in water below the LCST. The glass transition temperature (T-g) and onset temperature of degradation (T-d) of the PVSE300 were -72.5 and +317.5 degrees C, respectively. The hydrolytic stability of the PVSE300 in aqueous media was also examined and it was found that PVSE300 was fairly stable in cold water. The lithographic characteristics of PVSE300 were examined against UV and electron-beam (EB) exposure and it was found that the PVSE300 film showed a negative character when developed by cold water. The photosensitivity parameter, Dg(50), which denotes the dose at half remaining film thickness after development, against EB exposure was extremely high (1.0 mu C/cm(2)) when a probe current and an accelerating voltage was 100 pA and 20 kV, respectively. A high durability for O-2 reactive ion etching (O-2 RIE) was also observed. The characteristics of PVSE300 against photoirradiation were also examined.