Hollow polymer latex particles containing a hydrophilic core were prepared by seeded emulsion Polymerization with MAA/BA/MMA/St as comonomers, followed by stepwise alkalization treatment with ammonia. The size and morphology of composite latex particles was determined by TEM. The effects of the seeded emulsion polymerization conditions and alkalization treatment on the size and hollow structure of latex were investigated. The results showed that the optimum content of crosslinking agent in the shell polymers was about 0.5-1.0 wt %, emulsifier was about 0.8-1.1 wt %, and the core/shell weight ratio was 1/7. To obtain uniform hollow latex Particles with size, the starved feeding, technique should be adopted in seeded emulsion polymerization and the neutralization temperature should equal to the T-g of the shell polymer. Then, the obtained polymer particles under this condition had an excellent hollow structure. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 207-215, 2009