Kinetics of formation of 1:3 complexes from 1:1 and 1:2 complexes between Fe(III) and gallic acid (3,4,5-trihydroxybennzoic acid) has been studied. The rates were measured spectrophotometrically by monitoring the rise of absorbance at 500 nm (the wave length of maximum absorbance for the tris complex). The reaction was driven by providing a sudden pH jump to 8.0 along with an excess of ligand. Under these conditions, 1:3 complex would completely predominate. The observed pseudo first order rate constant increased with increasing ligand concentration initially, but leveled off at higher ligand concentration. The rate of formation of 1:3 complex from 1:2 complex was slower than it's formation from 1:1 complex by about an order of magnitude. The mechanistic implications of these rate measurements are discussed.