Diatto was an Italian manufacturing company founded in 1835 in Turin by Guglielmo Diatto to make 'carriages for wealthy customers'. In 1874 Guglielmo’s sons, Giovanni and Battista Diatto, began building railway carriages for Compagnie Internationale des Wagons-Lits and the Orient Express. In 1905 Guglielmo's grandsons, Vittorio and Pietro Diatto, began Diatto-Clément, a cooperative venture making motor-vehicles under license from French manufacturer Clément-Bayard owned by industrialist Adolphe Clément-Bayard. By 1909 they had full ownership of 'Autocostruzioni Diatto' and began developing their own motor-vehicles and exporting them worldwide.
From 1905 the company built two and four cylinder cars based on the Clément-Bayard, a leading contemporary French manufacturer. By the 1920s, Diatto was making quality cars of its own design, including race cars with supercharged eight-cylinder engines. Diatto also supplied frames to Bugatti which used them for their own race cars. Some Diatto racers were prepared and raced by Alfieri Maserati who left Diatto in 1926 to establish the Maserati marque with his brothers.
Diatto cars were known for their innovative engineering and as early as the 1920s they were equipped with four-wheel brakes and four-speed gearboxes.
Diatto ceased production in 1929.