PURPOSE: To obtain a catalyst for suitably polymerize to form polyvinyl ethers from vinyl ether monomers or vinyl ether polymers.

CONSTITUTION: In the mixture of compounds containing (A) approx. 0.5 to 100 pts.wt. H2C=CH-O group, a catalyst system comprising (B) approx. 0.5 to approx. 10,000 wt.ppm mixture of platinum catalysts in a platinum metal complex form and (C) approx. 1.0 to 20,000 wt.ppm, in terms of hydrogen, mixture in the form of a silicon hydride cocatalyst is incorporated. The cocatalyst (C) is organohydrosilane or organohydrosiloxane. This catalyst system (B, C) has such merits like that it is effective even in a small amount compared with ordinary catalysts and less in the residual catalyst amount left in the final cured resins, the metals contacting the resins are not easily eroded and that is shows an excellent solubility in vinyl ether monomers containing silicon, or the like.