There is a very delicate relation between the amounts of all the ingredients present in the cement composition and the properties of the product. In this study, homogeneous poly(methyl methacrylate) (PMMA) microspheres were prepared by suspension polymerization technique, and used in cement formulations. Various acrylic cements with different compositions were prepared by using PMMA microspheres, methyl methacrylate (MMA) monomer, radiopaque agent of barium sulfate (BaSO4), inorganic particles of hydroxyapatite (HA), initiator and chain stopping agent of 1-dodecyl mercaptan (DDM). The effects of these additives on mechanical and thermal properties of the resultant cements were examined. Addition of 8% HA relative to the solid parts caused an increase in both tensile and compressive strengths from 20.40 to 25.20 MPa, and from 84.04 to 89.57 MPa, respectively, while curing temperature was decreased about 3 degrees. Chain stepping agent of DDM caused a sharp decrease about 30 degrees in the curing temperature. Radiopaque agent of barium sulfate caused inverse effect on mechanical and thermal properties. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 4077-4084, 2009