In this study, gallic acid was separated by triphenylphosphine oxide in the presence of conventional solvents. Triphenylphosphine oxide is an organophosphorus extractant and highly selective towards carboxylic acids. Reactive extraction results were compared with physical extraction results. The extraction efficiencies reached up to 61, 76, 86, 67, and 84 % in the presence of triphenylphosphine oxide with oleyl alcohol, dimethyl adipate, isobutanol, methyl isopropyl ketone, and methyl ethyl ketone, respectively. Further, the number of theoretical units and the solvent to feed ratio were calculated for the practical design of a liquid-liquid extraction column. Roughly 2 to 4 theoretical units were calculated to meet the targeted extraction efficiencies. Gradient boosting algorithm showed a good performance to predict the results. This study is the first to investigate the reactive extraction of gallic acid by triphenylphosphine oxide, and include fundamental information for the recovery of gallic acid.