Was born at Schwechat, near Vienna; studied at the boys' seminary in Vienna with Albrechtsberger, who is said to have ranked him next to Mozart. He had expected to follow the law, but family reverses made it necessary for him to put into practice his musical knowledge instead. Here his friendship with Haydn and Mozart was of advantage to him, they recommending him to the publisher Artaria. Soon after this some of his compositions were brought out. He nursed Mozart in his last illness and the composer's widow requested him to complete the Requiem, which he began to do, but could not finish. In 1792 he became choirmaster of the Carmelite Church, in 1794 of the " Schotten " monastery in Vienna, in 1804 vice chapelmaster to the court, in 1810 musicmaster of the Emperor's children, and in 1824 succeeded Salieri as chief court chapelmaster. In 1834 he was struck with paralysis while conducting the Requiem of Mozart, and the year afterward received from the Emperor a title of nobility. He composed a number of concert works that were popular in his time; and many of church compositions are still used on the Continent. They include a "Requiem" of high merit, masses, Te Deums, and offertories.