A new layered organic–inorganic hybrid lead borate [Pb(en)0.5][B5O8(OH)] (1, en = ethylenediamine), has been hydro(solvo)thermally synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, FT-IR spectroscopy and thermogravimetric analysis, respectively. Compound 1 crystallizes in triclinic system space group P-1 (No. 2), a = 6.6537(6) Å, b = 6.7157(6) Å, c = 10.6911(9) Å, α = 99.015(7)°, β = 93.657(7)°, γ = 118.915(9)°, V = 407.59(6) Å3, Z = 2. The structure consists of two infinite borate layers constructed from [B5O8(OH)]2− cluster building units, then two such layers are further connected by the linear [Pb2(en)]4+ complex linkers to form the novel bilayer structure.