Crosslinked starch microspheres (CSMs) were prepared in an inverse suspension system. Scanning electron microscopy observation indicated that the CSMs were uniform in granularity with a smooth spherical particulate surface. The particle size analysis revealed that the average diameter was 18.2 mu m and that 85.8% of the microspheres were of a diameter below 30 pm. The structural characteristics of the carbonyl group and the second acrylamide by Fourier transform infrared spectroscopy of the CSMs showed that the soluble starch obviously crosslinked with N,N'-methylene bisacrylamide. The physical properties of the CSMs were analyzed by way of X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The results show that the crosslinking resulted in an increase in thermal stability and a decrease in crystallinity of the CSMs compared with soluble starch. The adsorption capacity of the CSMs increased with increasing concentration of methylene blue. The lower temperature was in favor of the adsorption capacity of the CSMs. The adsorption mode of methylene blue by the CSMs agreed more with the Langmuir isothermal equation. (C) 2008 Wiley Periodicals, tnc.