The invention is directed to a tin or bismuth catalyst/mercapto complex which exhibits substantially the same stability and activity after extended periods of storage as upon initial formation. This is achieved by restricting the vehicle for the catalyst complex to one that will not react with the mercapto compound upon extended storage of the catalyst system. These vehicles include aromatic hydrocarbons and terpenes. Ketone vehicles are excluded. Preferred vehicles include toluene, xylene, turpentine and d-limonene. Methods for forming the stabilized catalyst complex are claimed. Polymercapto/polyisocyanate resin formulations are claimed as more stable by the elimination of ketone vehicles. The cure rate of the resin formulations can be retarded by blending with acrylic resins. Stabilized tin catalyst complexes may also be used.
