LiCl-modified mesoporous silica SBA-16 has been successfully developed as a humidity-sensitive material. Its structure and morphology was characterized by XRD, IR spectroscopy, SEM and TEM. The thick film humidity sensor was based on Al₂O₃ceramic substrate with five pairs of Ag-Pd interdigital electrodes. The humidity sensitivity properties were measured using the ZL-5 model LCR analyzer at room temperature. The controlled-humidity environment was achieved by releasing super-saturation aqueous solutions of different salts of LiCl, MgCl₂, Mg(NO₃)₂, NaCl, KCl and KNO₃ in a closed glass vessel. The sensor showed excellent humidity sensitivity from 11% to 95%RH. The variation of the impedance was more than four orders of magnitudes. Besides, the sensor showed a very good repeatability in response and recovery with the response time and recovery time of approximately 10 and 25 s, respectively. The humidity sensing mechanism was studied. We found that the mesoporous structures contributed to the humidity sensitivity and an ionic transport mechanism was discussed based on the LiCl-modified mesoporous silica SBA-16 material.