Lactic acid, as a versatile chemical, was purified from fermentation broth by solid phase extraction with a spherical porous poly(4-vinylpyridine). Adsorption isotherm of lactic acid on poly(4-vinylpyridine) was first investigated with model solutions. The factors which affect the performance of separation and purification were then investigated. The obtained results indicate that the sorbent had a high adsorption capability of lactic acid, of which the maximum adsorbed lactic acid was 180.0 mg g(-1). Under the optimal condition the lactic acid was purified from fermentation broth by solid phase extraction with the purity of 88% and recovery yield of 95%. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2673-2677, 2011