Pyrolysis has shown that the polymetallic chelates of naphthazarin with Co(II), Ni(II) and Cu(II) assumed compositionally defined structures as [(C10H6O4)(M)2xH2O]yH2O where M stands for Co(II)/Ni(II)/Cu(II), x = 04, 04, 00, (coordinated water), y = 3, 11/2, and 4, (lattice water) respectively satisfying the metal ligancy. Each crystal of polymetal chelate assumed cubic symmetry with forbidden number 7, 15, 23 etc being absent. The inter planer spacing d (A0), a A0 (cell unit), of ρ g/cc and molecular weights of the polymetal chelates have been determined and reported. The calculated formula weight showed correspondence to the found molecule weight of each of the polymetal chelate. Keywords; Pyrolysis, Naphthazarin, Cubic, Crystallographics, X-ray