Ketalization reaction of poly(vinyl alcohol) (PVA) by acetone under acidic-catalyst/phase-transfer-catalyst was carried out easily and the structure of the product both swelled and dissolved in dimethyl sulfoxide-d(6) (DMSO-d(6)) was confirmed, which then indicated the structural change in the product polyvinylketal (PVKT) due to its hydrolysis in water, by NMR measurements. The effect of catalysts on reaction was probed from experimental viewpoint, compared with the theoretical calculation applicable to the previous classical method. It was observed that high ketalization degree PVKT was obtained with the presence of water and the effect of water on reaction was also probed in the present method, which may result in further application in the total syntheses of complex macromolecules from polyols and ketones. The behavior of PVKT in water under different conditions, which is very similar to that described in previous report, was also studied, as well as the specific viscosity (eta(sp)) of PVKT solution, and proper explanation is proposed. And the present study may lead to a further investigate of attractive intrinsic properties of PVKT. (c) 2005 Elsevier Ltd. All rights reserved.