When new rules in the railway operating regulations allowed higher axle loads and thus made more powerful locomotives possible, the S 9 was developed in Prussia. As with the S 7, the design was carried out as an Atlantic locomotive (wheel arrangement 4-4-2), but being 14.5 tonnes heavier. Although superheaters had been used across the board in most new locomotives in other German states since about 1905, for the time being no experiments were wanted with the S 9 and it was developed as a saturated locomotive. A four-cylinder compound engine was used for this in order to enable better utilization of the steam.

The firebox was extraordinarily generously dimensioned and had a grate area of four square meters, which was even a third larger than that of the later S 10. The power was ultimately limited by the cylinders, since these could only convert a certain amount of steam depending on the speed.

Two almost identical locomotives were designated S 8. In reality, these were S 9 which had been fitted with superheaters in 1913 and 1914. Their number remained at two, since it was not assumed that there would be a clear advantage in rebuilding all the remaining locomotives.

It was mainly used on the line between Berlin and Hanover. As with all four-coupled passenger and express locomotives, it was already evident before the outbreak of the First World War that these were no longer up to the demands of the rapidly growing traffic. Since some had to be handed in as reparations after the war and some were withdrawn in the period that followed, only three came to the Reichsbahn. These were the two S 8 with the numbers 14 001 and 14 002 and a single S 9, which became 14 031.