The title polymeric compound, catena-poly[dipotassium [bis[mu-N-salicylidene-beta-alaninato(2-)]-kappa(4)O,N,O':O";kappa(4)O":O,N,O'-dicopper(II)]-di-mu-isothiocyanato-kappa(2)N:S;kappa(2)S:N], [K[Cu(NCS)(C(10)H(9)NO(3))]](n), consists of [isothiocyanato(N-salicylidene-beta-alaninato)copper(II)](-) anions connected through the two three-atom thiocyanate (mu-NCS) and the two anti,anti-mu-carboxylate bridges into infinite one-dimensional polymeric anions, with coulombically interacting K(+) counter-ions with coordination number 7 constrained between the chains. The Cu(II) atoms adopt a distorted tetragonal-bipyramidal coordination, with three donor atoms of the tridentate Schiff base and one N atom of the bridging mu-NCS ligand in the basal plane. The first axial position is occupied by a thiocyanate S atom of a symmetry-related mu-NCS ligand at an apical distance of 2.9770 (8) A, and the second position is occupied by an O atom of a bridging carboxylate group from an adjacent coordination unit at a distance of 2.639 (2) A.