The title complex [La(betaine)(2)(H2O)(6)Fe(CN)(6)](.)2H(2)O (betaine = (CH3)(3)NCH2CO2) has been synthesized and characterized by X-ray single-crystal structure analysis. The crystal crystallizes in monoclinic, space group P2(1)/n with a = 15.793(5), b = 8.927(3), c = 22.257(7) A angstrom, P = 110. 147(5)degrees, C16H38FeLaN8O12, M-r.= 729.31, Z = 4, V = 2946.0(15) angstrom(3), D-c, = 1.640 g/m(3), mu(MoK alpha) = 1.988 mm(-1), F(000) = 1476, R = 0.0388 and wR = 0.0827. for 4237 observed reflections (I > 2(l)). The La3+ Ion is nine-coordinated by one cyano nitrogen atom and eight oxygen atoms of two betaine and six water molecules. Each complex molecule is connected to form a 3D network structure by some 0-H... 0 and 0-H... N hydrogen bonds.