In order to modernize the locomotive park on the Sicilian network and to ensure the operation of passenger trains on new routes, Guglielmo Cappa developed the class H. Since the same maximum speed should be achieved in both directions and the locomotives should also be able to be used on secondary routes, it was designed as a tank locomotive with a 2-6-2T wheel arrangement and an axle load of 14 tonnes. It was powered by a two-cylinder compound engine with a high-pressure cylinder on the left side. In order to ensure sufficient traction on the mountainous routes in Sicily, the coupled wheels were designed with a diameter of just 1,510 mm.

The first six pieces were delivered to the Rete Sicula in 1905 and numbered 401 to 406. The next six have already been taken over directly by the FS and, together with the first ones, have been classified in the number range from 9101 to 9112. Since the good acceleration of the locomotives was also suitable for suburban traffic, another 42 units were ordered and stationed in Milan. The remaining machines soon came to Milan and were used there until 1955. Some engines had come to Yugoslavia during World War II and remained there after the war ended.

One example was experimentally converted into a diesel Zarlatti locomotive in 1929. The boiler was replaced with a two-stroke diesel with a compressor and connected compressed air tank. The engine filled the tank and the compressed air was eventually used to power the steam locomotive's original cylinders. Although this principle worked in general, it still had technical difficulties and was not pursued further.