Ring-opening suspension polymerization of p-dioxanone (PDO) in supercritical carbon dioxide (scCO2) was investigated in the presence of poly(caprolactone)-perfluropolyether-poly(caprolactone) (PCL-PFPE-PCL). The molecular weight, yield and particle morphology of poly(p-dioxanone) (PPDO) were studied. The stabilizer was effective to stabilize the ring-opening polymerization (ROP) of PDO in SCCO2, leading to the formation of resorbable microparticles in a "one pot" procedure. The mean size of PPDO microparticles obtained from suspension polymerizations was sensitive to the rate of agitation and the stabilizer concentration. The method to generate PPDO microparticles has overcome its unprocessable drawback with common organic solvents and provided new product form for biomedical applications.