We have synthesized the compound meso-tetra(4-pyridyl)porphyrinatothallium (III) acetate, Tl(tpyp)(OAc), by using a new procedure, and characterized its structure through 1H/13C NMR spectroscopy, elemental analysis and the FABMS technique. The free energy of activation ΔG‡233 for the acetato group exchange between Tl(tpyp)(OAc) and acetic acid in CD2Cl2 solvent has been derived to be 41.6±0.3 kJ mol-1 through 1H NMR temperature-dependent measurements. The Correlation Spectroscopy via Long-Range Coupling technique (COLOC) was used to resolve two quaternary carbons, i.e. Cα and C-1 of Tl(tpyp)(OAc) at 149.6 and 149.8 ppm, respectively, at 21°C. In the slow exchange region, the methyl and carbonyl carbons of the acetato group are separately located at 17.6 ppm [with 3J (Tl-13C) coupling constant 314 Hz] and 174.1 ppm [with 2J (Tl-13C) coupling constant 256 Hz], for the Tl(tpyp)(OAc) case, and at 21.3 and 178.4 ppm for the HOAc case.