Potentiometric studies on complexation reaction between Al3+ (which has recently been implicated in neurological dysfunctions including Alzheimer's disease) and 3,4,5-Trihydroxybenzoic acid (gallic acid) and its methyl ester has been investigated. A computer program BEST was use to analyse the data. It is found that gallic acid form 1:1 complex up to pH 8.5 and a 1:2 complex between pH 8.5 and 11.0. Log beta1 and log beta2 values are 18.76 and 29.52, which are higher than those of Fe3+ complex of the same ligand. The methyl ester of gallic acid forms 1:1, 1:2 as well as 1.3 complexes with log beta1 log beta2 and log beta3 values of 23.8, 33.83 and 39.63 respectively. Implications of these formation constants for polyphenol complexes of Al3+ upon Al absorption and resulting toxicity are discussed.