Complex [Co(HOC10H6COO)2(H2O)4] was synthesized by reaction of hydroxy-2-naphthoic acid with CoCl2·6H2O. The compound was characterized by elemental analysis, IR and the structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21 / n with a=0.675 8(2) nm, b=0.518 15(14) nm, c=2.962 9(9) nm, β=94.925(8)°. V=1.033 6(5) nm3, Z=2, D=1.624 Mg·m-3, F(000)=522. The Co atom has an octahedron coordination geometry and was six-coordinated with two oxygen atoms from two carboxylate ligands and four oxygen atoms from four water molecules. The complex molecules were linked by different hydrogen bonds to form a 2D network. The complex has thermal stability and shows a strong fluorescent emission at 421 nm (λex=342 nm). CCDC: 250903.