In 1831 he took part in Lebeau's cabinet as minister without portfolio – it was Devaux who suggested Leopold of Saxe-Coburg-Gotha as a candidate for the throne of Belgium.
I 1831 blev han minister uden portefølje i Lebeaus regering – det var Devaux som foreslog Leopold af Sachsen-Coburg-Gotha som kandidat til den belgiske trone.