A process for producing organic acid di- or tri-esters, particularly citric acid tri-esters, with the available acid groups esterified using countercurrent reactive distillation using acid catalysts in a structured packing is described. In the reactive distillation an organic acid di- or tri-ester is formed by chemical reaction and purified to its final state within the single column. Organic acid di- or tri-esters are produced at relatively low cost, with less waste production in by-products of the reaction, and in a less complicated manner than prior processes. Organic acid di- and tri-esters have uses as solvents, as plasticizers and in conversion products.