As basic research for the solution spinning of the high T(c) oxide superconductor, the effect of organic acid on the complex formation of poly(vinyl alcohol) (PVA) with the copper [Cu(II)] ion was explored with various carboxylic acids, such as formic acid, acetic acid, n-butylic acid, and lactic acid. The effects of these acids on the interaction between PVA and Cu (II) acetate in aqueous solution were nonexistent, while a chelation of the Cu(II) ion and lactic acid was detected. In the solid state, a linear complex of PVA with the Cu(II) ion was formed by adding organic acid. The ligand of the linear complex was highly dependent on the kind of acid used.