A ruthenium-containing metathesis catalyst system which contains a ruthenium compound (A), a phosphorus compound (B), and a compound (C) containing one carbon-to-carbon triple bond. The mole ratio of compounds A:B:C is typically in the range of about 1.0:0.01-100:0.01-100. The ruthenium compound (A) is a Ru(II), Ru(III), or Ru(IV) compound containing an anionic ligand (X) and optionally an arene ligand and optionally a phosphorus compound ligand. The compound (B) is optional if the ruthenium compound (A) contains a phosphorus-containing ligand. |