He served as French minister in several European capitals. He was mayor of Rochelle in 1789, and was elected by the district of Aunis to the Estates-General. When the Assembly adjourned, he became President of the Criminal Tribunal of the Department of Seine et Oise, and was sent as their representative to the National Convention in 1792.
In that Convention, he voted for the death of King Louis XVI. He assisted in the organization of Holland after its conquest by the French armies.
In 1795 he was appointed Secretary to the Council of Ancients, one of the organs of the Constitution of the Year III under the Directorate. He began his diplomatic career in 1798 with the appointment as Minister Plenipotentiary to Bavaria, where he served until March, 1799, at the approach of war.
Back in France he was made Receiver-General of the Department of Seine et Oise, but on the overthrow of the Directory on the 18th of Brumaire, he returned to the diplomatic service on behalf of the new Consulate. In March, 1800, he was appointed by First Consul Bonaparte and Foreign Minister Talleyrand as Minister in Madrid.
When he was replaced in Madrid at the end of 1800 by Lucien Bonaparte, he was sent to Florence in February of 1801, as Minister Plenipotentiary, to arrange peace with France.
He conducted the negotiations which regularized the French conquest of Tuscany by its formal cession to France. He moved to the Court of Naples in March and became French Minister there in April, 1801. When a combined British-Russian fleet and army entered the ports of the Kingdom, Alquier left Naples.
He returned to Paris in February, 1808.
In 1810-1811, he was sent to Stockholm as Envoy Extraordinary, and served as Minister in Stockholm, and in 1811-1814 in Copenhagen. His mission was to enforce the "Continental System" of Napoleon against the British and Russian commercial interests.
In 1813, he concluded a defensive-offensive alliance with Denmark. With the fall of Napoleon Alquier was recalled, and with the return of the Monarchy under Louis XVIII, he was condemned to exile as a regicide.
He was allowed to return to France in 1818, with the consent of the King.
He died in Paris on February 4, 1826.
Council of Five Hundred]
He was a member of the Constituent Assembly, and served on several committees. He became one of the secretaries of the Constituent Assembly.