A method for synthesizing inorganic-organic layered compounds is proposed using a biphasic liquid-liquid system in one pot. Layered basic zinc benzoate (LBZB) compounds were chosen, and their formation was investigated starting from a xylene-water system. In a typical synthesis, a xylene phase dissolving benzoic acid was allowed to stand in contact with an equal amount of an aqueous phase dissolving zinc nitrate hexahydrate and urea. A role of urea is to supply OH(-) gradually by hydrolysis at an elevated temperature. The biphasically separated solutions were maintained at 80 °C, and then LBZB was obtained in the aqueous phase. Two kinds of layered structures with a basal spacing of 27.14 and 14.77 Å were formed by changing a C(6)H(5)COOH/Zn molar ratio. Chemical compositions of the 27.14 and the 14.77 Å layered phases were estimated to be Zn(OH)(1.74)(C(6)H(5)COO)(0.26)·0.29H(2)O and Zn(OH)(1.12)(C(6)H(5)COO)(0.88)·0.21H(2)O, respectively. The 27.14 Å phase could also be deposited as a film on substrates by heterogeneous nucleation. The film consisted of standing platelike particles and exhibited a two-dimensional structure, which could be converted to ZnO by heating. The relationship between the initial solution compositions and the final solid products was systematically examined on the basis of distribution law for benzoic acid in the xylene-water system.