K2CO3-SBA-15 with different K2CO3 content was prepared by thermal dispersion. The structures of resultant powders were characterized by XRD, N-2 adsorption and IR. The humidity sensing properties of the powders were also investigated. Compared with pure SBA-15, K2CO3-SBA-15 shows improved humidity sensing properties and the introducing level of K2CO3 has a great influence on the humid sensitivity of K2CO3-SBA-15 composites. The optimal mixing ratio was K2CO3-SBA-15 (0.8 g/g), which exhibited excellent linearity in the whole range of 11-95% RH, a resistance variation of about five orders of magnitude, and a rapid response time and recovery time about 15 and 50 s, respectively. The mechanism of the humidity sensitive properties was also discussed. (C) 2009 Elsevier B. V. All rights reserved.