Palladium(II) acetate in acetic acid in the absence of acetate ion exists as the trimeric species Pd3(OAc)6. The reaction of the trimer with NaOAc or LiOAc at 25° was not instantaneous. Spectral studies on fully equilibrated systems indicated the first equilibria involved transformation of trimer to dimer[Formula: see text]with K32 = 7.77 × 104 M−5 and K′32 = 1.76 × 102 M−5. The kinetics of the slow transformation of trimer to dimer was studied. The reaction has the rate expression: rate = [Pd3(OAc)6] (k + k′[MOAc]) (M = Li or Na). This rate expression is consistent with substitution processes suggesting the slow step of the reaction is the SN2 attack of solvent or acetate on a Pd(II)–acetate bond to break one of the acetate bridges.In the NaOAc system conversion of trimer to dimer was complete at 0.2 M NaOAc. Further addition of NaOAc caused the dimer to be converted to monomer.[Formula: see text]