Abstract: In an acetate buffer medium of pH 5.8-6.2,a charge transfer complex with molar composition ratio of 1 to 1 was formed between amoxicillin (AMXL) and p-benzoquinone,with its absorption maximum at 476 nm and molar absorptivity of 2.0×103L·mol-1·cm-1.Beer′s law was kept in the concentration range of AMXL within 200 mg·L-1.The proposed method was used in the analysis of AMXL preparations,giving results in consistency with the results obtained by the pharmacopia method.Values of RSD′s (n=6) obtained by this method were less than 1.5%.