When the Mariazell Railway was electrified between 1908 and 1911, both the trackside equipment and the locomotives were to be supplied by the Austrian Siemens Schuckert Works (ÖSSW). For the first time in history, a longer stretch of track was electrified with one-phase AC. Here, the system of choice was a unique combination of 6,500 Volts at a frequency of 25 Hertz. 16 locomotives were built which were designated class E by the NÖLB.

While the electrical part of all locomotives came from ÖSSW, the mechanical part of only 13 was built by Krauss at Linz. Two came from Floridsdorf and one from Weitzer at Graz. The locomotives stood on two bogies each which had three axles and one unsprung traction motor that transmitted its power via a crank axle and coupling rods. Each locomotive had one of two different gear ratios either for the flatter or steeper sections of the line.

In 1923, the line came under the control of the BBÖ and the class was still named E. In 1923, the gear ratios of all locomotives was equalized. In 1938 the Reichsbahn designated them E 99 and likewise, the ÖBB called them class 1099 after the war. Between 1959 and 1962, they were rebuilt thoroughly where most of their electric equipment and their outer appearance changed.

Only in the year 2000, the first locomotives were stored. In 2010, the ownership of the Mariazell Railway changed from the ÖBB to the NOVÖG. Soon more were retired after new Stadler EMUs had been introduced. In 2013, more than 102 years after their introduction, the last one was retired from regular service. But some continued to be used for tourist trains, for snow clearing or in construction trains.