A commercial surgical bone cement has been modified by adding tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA). The effects of the addition of TCP, HEMA, and EGDMA on the vinyl polymerization kinetics and thermal stability of the bone cement have been evaluated. The reaction rate constants (k) were determined from a kinetic analysis. The separate and combined effects of TCP, HEMA, and EGDMA contents on the rate and the heat of polymerization can be explained by the frequency factor and the activation energy. The decomposition temperature of the modified acrylic bone cement was studied by thermogravimetry. The decomposition temperature increased with TCP content, whereas HEMA and EGDMA had little effect on the decompositon temperature.