The reduction of nitrate in nitrogen using bimetallic palladium tin catalysts and hydrogen is an interesting process for water treatment. The aim of the present study is to use formic acid (FA) as a reducing agent and a pH buffer in order to substitute the mixture of hydrogen and carbon dioxide. The catalytic performances of a palladium tin catalyst supported on silica were evaluated in the presence of FA, as a function of the initial acid concentration and of the gas phase (N(2), CO(2), or H(2)). Results were compared to those obtained with hydrogen in the presence of carbon dioxide. Similar mechanisms seem to explain the identical catalytic performances observed with these two reducing agents.