Two new inorganic-organic hybrid materials based on heteropolyoxometalates, (C₄H₁₀N)₆ (P₂ Mo₁₈O₆₂).4H₂O I, and (C₄H₁₀N)₆ (As₂Mo₁₈O₆₂).4H₂O II, where C₄H₁₀N is protonated pyrrolidine have been synthesized and structurally characterized by physic-chemical methods. Single-crystal X-ray diffraction method, infrared, ultraviolet spectroscopy, Thermogravimetricanalysis andcyclic voltammetry measurements of the title hybrid materials indicate that there are hydrogen bond interaction between O atoms of the hetero-polyoxometalates and water molecules as well as the N and O atoms of the organic compound. The molecular structures of synthesized hybrid materials contain discrete entities of pyrrolidinumion and water molecules surround every [X₂Mo₁₈O₆₂]⁶⁻ anion over the extended crystalline network that the [X₂Mo₁₈O₆₂]⁶⁻ anion retains its ``Dawson structure". Crystal data: I monoclinic, space group P2₁/a, a = 13,453(1) Å, b = 24,046 (1) Å, c = 24,119(1) 𝛽 = 97, 99(1)°, V = 7726,30(5) ų and Z = 4; II monoclinic, space group P2₁/a, a = 13.4900(1) Å, 24.0900(1) Å, 24.2740(1) Å, 𝛽 = 98.320(1)°, V = 7805.40(7) ų and Z = 4.