Novel Fe3O4/poly(styrene (St)-acrylic acid (AA)) magnetic porous beads (MPBs) were fabricated by a seed swelling process using magnetite particles as seeds. The porous beads were characterized with scanning electron microscopy (SEM). Magnetic properties of the MPBs were obtained by electron spin resonance (ESR) and vibrating-sample magnetometer (VSM). All the observations indicated that the beads were ferromagnetic. Thiobacillus thioparus was immobilized to the porous carrier at up to 9.3 x 10(9) cells/g MPBs. Compared with active carbon (AC) and agar as carriers, MPB as a carrier of immobilized Thiobacillus cells is the most efficient in removal of sulfide. Effects of the size of MPBs and surface carboxyl content on cell immobilization efficiency were investigated and the optimal pH and the temperature for the immobilized cells were determined. T thioparus immobilized on MPB had a good storage stability. Continuous operation of a magnetically stabilized fluidized bed (MSFB) filled with MPB-immobilized T thioparus at a flow rate of 160 ml/min resulted in the sulfide oxidizing rate of 8.64 kg S m(-3) d(-1). (c) 2005 Elsevier Inc. All rights reserved.