Abstract: The complex of trimesic acid-nickel was synthesized at room temperatuer with 1,3,5-benzoic acid as ligand, Ni²⁺ as center ion and water as solvent. X-ray diffraction was used to characterize the crystal structure. We studied the frequency characteristics, response recovery characteristics and humidity sensing characteristics, tested and analyzed the humidity sensing mechanism. The results show that the crystal unit structure is ［Ni₃(BTC)₂·14H₂O］·2H₂O(CCDC: 1990438), and the complex has zero dimensional structure. The linear relationship of humidity sensitive characteristic curve is good in the medium and high humidity area（54%—97% RH）, the recovery time is 2 s, and the humidity sensing performance is excellent, which is suitable for the detection of humidity sensing materials in medium and high humidity environment.

Key words: trimesic acid, metal-organic coordination compound, humidity sensing