X-ray powder diffraction data, unit cell parameters, and space group for a new organometallic compound, lanthanum trilactate trihydrate, LaC9H21O12, are reported [a = 9.986(1) Å, b = 9.158(1) Å, c = 11.200(1) Å, α = 115.08(1), β = 117.41(1), γ = 88.61(1), unit cell volume V = 804.70 Å3, Z = 2 and space group P1]. All measured lines were indexed. No detectable impurity was observed.