The new ternary lithium copper aluminide, Li(12)Cu(16+x)Al(26-x) (x = 3.2), dodecalithium nonadecacopper tricosaaluminide, crystallizes in a new structure type with space group P4/mbm. Among nine independent atomic positions, two Al (one of which is statistically disordered with Cu) and three Li atoms have point symmetry m.2m, two statistically disordered Al/Cu atoms are in m.. sites, one Al atom is in a 4/m.. site and one Cu atom occupies a general site. The framework of Li(12)Cu(16+x)Al(26-x) consists of pseudo-Frank-Kasper polyhedra enclosing channels of hexagonal prisms occupied by Li atoms. The crystallochemical peculiarity of this new structure type is discussed in relation to the derivatives from Laves phases (LiCuAl(2) and Li(8)Cu(12+x)Al(6-x)) and to the well known CaCu(5) structure.