Ca_1-xB₂C₄ (x ~ 0.08) and Ca_1-xB₂C₆ (x ~ 0.04) are two compounds containing heterographene-B,C nets which were prepared by solid state synthesis and structurally characterized by X-ray powder diffraction data. Both compounds crystallize in the space group P6/ mmm (No. 191). The lattice constants are a = 4.55971(5) Å and c = 4.4020(1) Å for CaB₂C₄ and a = 2.58390(5) Å, c = 4.43597(8) Å for CaB₂C₆. The calcium atoms are intercalated between the heterographene (B,C) nets. The calcium atom distribution in Ca_1-xB₂C₆ is disordered, leading to diffuse scattering. A model for this disorder was developed that matches well the observed diffuse scattering observed in the electron diffraction pattern. For Ca_1-xB₂C₆ and its decomposition products magnetic and electric properties are being reported.