It is very important to understand the curing kinetics of moisture curable one part sealants in order to design and handle them. The curing kinetics of the representative sealants are measured and their kinetic models are studied. If the quasi-steady-state is assumed, the cured time represents the quadratic equation of cured depth. Their parameters are determined, and depend upon the physical properties of the materials and their curing mechanism. The experimental cure speed agrees well with the calculated model. Ii the permiability of moisture through the cured film is faster, the cure speed of the sealant becomes faster. This correlation is certified by experiments and the presented kinetic model. A sealant whose cure speed is very slow in the range of low humidity, however, depends not on the permiability of moisture but on the reaction mechanism. The presented model has to be mended when the reverse reaction is taken into account on or in the region oi the small cured depth where quadi-steady-state is not right.