At the age of 23, Payen became manager of a borax-refining factory, where he developed a process for synthesizing borax from soda and boric acid. Previously, all borax had been imported from the East Indies exclusively by the Dutch. Payen’s new method of synthesizing borax allowed him to sell the mineral at one third the going price, and break the Dutch monopoly.
Payen also developed processes for refining sugar, along with a way to refine starch and alcohol from potatoes, and a method for determination of nitrogen. Payen invented a decolorimeter, which dealt with the analysis, decolorization, bleaching, and crystallization of sugar.