English: The rate of product formation in the cyanosilylation of ketones shows a slight non-linear dependance on catalyst loading at high catalyst concentrations. a) This observation, among others, is accounted for by the reversible formation of inactive catalyst complexes. b) Similar behavior at multiple conversion points is consistent with one dominant mechanism operating over the entire course of the reaction. The mechanistic scheme and kinetic data are adapted from independent kinetic simulations using the rate and equilibrium constants reported for the amino-thiourea catalyzed cyanosilylation of ketones by Zuend, S. J.; Jacobsen, E. N. J. Am. Chem. Soc. 2007, 129, 15872.