ABSTRACTThe objective of this study was to determine the antibacterial effectiveness of selected hydroxycinnamic acids (caffeic, ferulic, pcoumaric) againstEscherichia coliandStaphylococcus aureusat pH 5.0, 6.0 and 7.0 andBacillus cereusat pH 6.0, 6.5 and 7.0. p‐Coumaric acid was generally the most effective inhibitor tested causing<99.9% inhibition ofE. coliat 1000 μg/ml (pH 5.0, 48 hr),S. aureusat 500 μg/ml (pH 5.0, 48 hr), andB. cereusat 500 μg/ml (pH 7.0, 9 hr). Inhibition increased as pH decreased withE. coliandS. aureusbut notB. cereus. Bacillus cereusappeared to be the most susceptible strain with 1000 μg/ml of the compounds tested causing<99% inhibition at all three