With spectrophotometric method, the completes of iron (Ⅲ) and 8-quinolinol formed in acid solution were studied. It is found that the position of absorption maximum varies with pH value of their solutions. In excess of 8-quinolinol, 1:1 complex formed in solutions of pH < 2.2, with absorption matimum at 645 nm; while in solutions of pH from 3.0 to 3.2, a 1:2 complet, [FeOx₂]⁺,etists with absorption maximum at 605 nm (see Fig.1 and 2).Above pH 3.32, a precipiate forma. In excess of iron (Ⅲ),1:1 complex appears in solutions of pH<2.5, and in solutions of ca. pH 3.1, both 1:1 and 1:2 complexes occur side by side (see Fig.7).