Poly(vinyl alcohol) (PVA) having a number-average degree of polymerization of 7000 was obtained from the poly(vinyl acetate) (PVAc) having a number-average degree of polymerization 9000, a product of photo-induced emulsion polymerization of vinyl acetate (VAc), carried out at 0degreesC, using poly(oxyethylene)(10) nonyl phenyl ether ammonium sulfate as an anionic emulsifier. It was found that 100% conversion is always attained in the whole range of the investigation and the emulsifier plays an important role in the initiation process. The applicability of the photo-induced emulsion polymerization system to a relatively large-scale production was tested by using an apparatus equipped with an internal high-pressure Hg lamp with a capacity of several hundred grams per batch under nitrogen atmosphere. It was found that both the rate of polymerization and the degree of polymerization of resulting polymers are slightly lower than those obtained from corresponding small-scale polymerizations prepared on a high vacuum system because of the presence of oxygen.