A homometallic mixed-ligand complex Pb(BTA)(phen)·H2O was synthesized by taking hydrated N,N′-bis(1H-tetrazolyl)amine (H2BTA·H2O), 1,10-phenanthroline (phen) and PbCl2 as starting materials during this work. The complex was characterized by elemental analysis, IR, UV-Vis, FS and X-ray single-crystal diffraction. The results reveal that the coordination number of the Pb ion is four and the geometry can be regarded as a square-pyramidal geometry, with two N atoms of BTA2- and two N atoms of phen at the base. Crystal data for it, C14H11N11OPb, monoclinic, space group C2/c, a = 9.420(2) Å, b = 22.943(6) Å, c = 15.286(4) Å, α = 90.000°, β = 105.760(4)°, γ = 90.000°, V = 3179.6(14) Å3, Z = 8, final R indices [I > 2σ(I)], R1 = 0.0241, wR2 = 0.0471. The thermal stability of the complex was investigated by thermogravimetric analysis. The TG profile indicates that Pb(BTA)(phen) is thermally stable up to the temperature of 588.9 K.