The triphosphate dodecahydrate of cobalt and sodium CoNa3P3O10.12H2O was prepared by the ion exchange resin process. Its structure was studied by X-ray diffraction and determined in the monoclinic space group P121/c1 with the unit-cell parameters a = 14.6650(5) Å, b=9.1916(3) Å, c = 15.0239(5) Å, β =90.2210(10) °, Z = 4 and V = 2025.13(12) Å3. The thermal dehydration of this compound was performed, leading to an anhydrous new form, CoNa3P3O10, which was characterized by X-ray diffraction. The obtained CoNa3P3O10 crystallized in monoclinic space group P21/n with the unit-cell parameters a=15,3774 Å, b=7,6988 A°, c=14,2832A°, β=92,9115°. The characteristic IR wavenumbers of the P3O105− ions observed in the vibrational spectra were calculated using isotopic substitutions, which confirms the existence of these groups in the studied compound. A comparison between the IR and Raman wavenumbers of CoNa3P3O10.12H2O, CoNa3P3O10 and Na5P3O10.12H2O was performed. A kinetic study was also made for CoNa3P3O10·12H2O.