In the title heterodinuclear complex, [CuNa(BF(4))(C(8)H(7)O(3))(2)](n), the Cu(II) ion is four-coordinated by four O atoms of two 2-formyl-6-meth-oxy-phenolate ligands, giving rise to a square-planar geometry. The Na(+) ion is six-coordinated by four O atoms from the two ligands and two F atoms of two tetra-fluoridoborate anions. The tetra-fluoridoborate anion links the Na(+) ions, forming a one-dimensional structure along [001]. Three F atoms of the tetra-fluoridoborate anion are disordered over two sets of sites, with an occupancy ratio of 0.790 (11):0.210 (11).