Abstract: A new inclusion compound, (nC_4H9)_4N⁺(p-HOC6H_4CO2^-)·(p-HOC_6H4CO2H), was prepared and characterized by X-ray crystallography. Crystal data: Orthorhombic, space group Pna2₁ (No. 33), a = 1.632(2)  nm, b = 1.371 8(19)  nm, c = 1.396 3(19)  nm, β= 90 °, V=3.127(7)  nm³, Z = 4, R₁＝0.062 4, wR = 0.153 6.  In the crystal structure, phydroxybenzoic acid molecules and phydroxybenzoic acid anions are joined through O—H…O hydrogen bonds to form corrugated dimensional hydrogen bonds layer paralleling to the (100) family of plane. The tetrabutyl ammonium cations are stacked the gap between the layers to form a typical “sandwich” hydrogen bonds structure, which the interlayer distance is about a/2 = 0.816 nm.