Lithium acrylate (LiAA) was in situ prepared in a chlorinated polyethylene (CPE) matrix through the neutralization of lithium hydroxide (LiOH) and acrylic acid (AA) during mixing. The obtained compounds were vulcanized with dicumyl peroxide (DCP). The in situ preparation and polymerization of LiAA were characterized with Fourier transform infrared spectrometry. The crosslink density analysis results indicated that the CPE/LiAA vulcanizates contained both covalent bonds and ionic bonds. The effects of the DCP and LiAA contents on the mechanical properties and water-swelling properties of the CPE/LiAA vulcanizates were studied. The relationship between the LiOH/AA molar ratio and the properties of the CPE/LiAA vulcanizates was investigated. The results showed that LiAA could improve the mechanical and water-swelling properties of CPE/LiAA vulcanizates, providing a new approach to the preparation of water-swelling elastomers. (C) 2004 Wiley Periodicals, Inc.