Novel pH-responsive polyglycerol (PG)based hydrogels were successfully synthesized through the reaction of epichlorohydrin with L-lactic acid (LLA) in the presence of sodium hydroxide (NaOH), and cetyltrimethylammonium bromide as a phase transfer catalyst at room temperature, followed by hydrolysis, polymerization, and crosslinking reactions. The resultant gel was characterized by carbon nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared measurement, and it was found that incorporated LLA was bound to PG network as a pendant acidic substituent by the hydroxyl group of LLA (PGL gel). The PGL hydrogels with different LLA contents and equilibrium swelling ratios (ESRs) were prepared by changing the feed ratios of materials. The results determined by chemical titration showed that under the applied conditions the efficiency of introducing the carboxyl group into PG network was about 86% and the amount of LLA in the hydrogel reached to about 17 wt %. The swelling behavior of the hydrogels in different environmental mediums was investigated, and the results showed that the hydrogels are pH-, ionic strength-, and cationic charge-responsive. The hydrogels also have the reversible swelling/deswelling properties. These pH-responsive PG-based hydrogels will have potential applications in biomedical and related areas. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 3209- 3216, 2009