The Pd-L ligand bond dissociation energies (BDEs) of cis- and trans-[L-Pd(PH3)(2)Cl](+) were predicted using coupled cluster CCSD(T) theory and a variety of density functional theory (DFT) functionals at the B3LYP optimized geometries. trans[L-Pd(PH3)(2)Cl](+) is the more stable isomer when Pd forms a donor-acceptor bond with a C atom of the ligand, including the pi-bond in norbomene; for the remaining complexes, the cis-[L-Pd(PH3)(2)Cl](+) isomer is substantially lower in energy. For cis-[L-Pd (PH3)(2)Cl](+) complexes, the Pd-L bond energies are 28 kcal/mol for CO; similar to 40 kcal/mol for AH(3) (A = N, P, As, and Sb), norbornene, and CH3CN; and similar to 53 kcal/mol for CH3NC, pyrazole, pyridine, and tetrahydrothiophene at the CCSD(T) level. When Pd forms a donor-acceptor bond with the C atom in the ligand (i.e., CO, CH3NC, and the pi-bond in norbornene), the Pd-L bond energies for trans[L-Pd(PH3)(2)Cl](+) are generally similar to 10 kcal/mol greater than those for cis-[L-Pd(PH3)(2)Cl](+) with the same L; for the remaining ligands, the ligand bond energy increases are similar to 3-5 kcal/mol from cis-isomer to the trans-isomer. The benchmarks show that the dispersion-corrected hybrid, generalized gradient approximation, DFT functional omega-B97X-D is the best one to use for this system. Use of the omega-B97X-D/aD functional gives predicted BDEs within 1 kcal/mol of the CCSD(T)/aug-cc-pVTZ BDEs for cis-[L-Pd(PH3)(2)Cl](+) and 1.5 kcal/mol for trans[L-Pd(PH3)(2)Cl](+).