Reversible oxidative addition of the B-CN bond to palladium was observed in a reaction of a C-13-labeled cyanoborane, having an N,N'-dimethyl-o-phenylenediamido ligand on the boron atom, with a palladium-PMe3 complex, which was generated from (pi-cyclopentadienyl)(pi-allyl) palladium(II) with 2 equiv of PMe3. The same borylbis( trimethylphosphine)palladium( II) cyanide complex was formed in the reaction of borylbis( trimethylphosphine) palladium( II) chloride with trimethylsilyl cyanide. Reaction of the palladium-PMe3 complex with a cyanoborane bearing a tethered carbon-carbon triple bond gave a (2-borylalkenyl) palladium( II) cyanide complex, whose structure was determined by a single-crystal X-ray analysis, Via insertion of the C-C triple bond into the B-Pd bond of a transiently formed borylpalladium( II) cyanide complex. The (2-borylalkenyl) palladium( II) cyanide complex underwent reductiVe elimination at 60 degrees C. Significant retardation of the reductiVe elimination step by addition of 2 equiv of trimethylphosphine was observed.