Cobalt dimethylphenylpiperazinium cyclotetraphosphate hexahydrate, Co[C 12 H 19 N 2 ] 2 P 4 O 12 .6H 2 O, was synthesized by a reaction between cyclotetraphosphoric acid H 4 P 4 O 12 , cobalt carbonate, and 1-(2,4-dimethylphenylpiperazine). It crystallizes in the triclinic system, space group P, with the following unit cell parameters: a = 7.336(1), b = 8.413(1), c = 14.926(2) Å, α = 87.46(1), β = 83.13(1), γ = 82.98(1)°, V = 907.3(2) Å 3 , and Z = 1. The atomic arrangement can be described as layers containing P 4 O 12 rings a and Co(H 2 O) 6 octahedra spreading in the (001) planes between which are located the dimethylphenylpiperazinium groups via H-bonds. The synthesis and characterization by X-ray diffraction, IR absorption, and thermal analysis are described. [ABSTRACT FROM AUTHOR]