This line, dating from 1931, is the youngest in the Steiermarkische Landesbahnen group of railways. Originally conceived as part of a trunk route between Wien and Novi, only the section between the spa town of Bad Gleichenberg and the Federal Railway at Feldbach was built, and was electrified using DC current. The line was first promoted in April 1886, but finance was not made available to make a start. 14 April 1886 first projects of a railway connection from field brook to bath same mountain

During the First World War a prisoner of war camp was established at Mühldorf, later to become a military field hospital, and a temporary line was laid as far as the camp.

After the war, the Steiermark Govenrment reasserted the intention to build the line, and a concession for 90 years was granted on 10th December 1928. The line opened for both goods and passengers on 20 June 1931, being operated by the Lokalbahn Feldbach - Bad Gleichenberg.

During World War 2, the Lokalbahn was taken over by the Federal Railway, and in April 1945 closed because it was in an area of conflict. The line did not restart operations until 01 November 1947, and then with a steam engine as the electrical generating equipment had been damaged. Electrical operation restarted from 15 November 1948. Between 1962 and 1970, the Federal railway, ÖBB, ran through trains to and from Wien, using class 5146 (Blauer Blitz) units, and 5045 single units, sometimes hauling trailers. Five years after the service ended, one of the original mercury-arc rectifiers in the power plant was replaced by a silicon diode unit.

In 1980 one of the original railcars, ET1, was completely modernised, with a new superstructure and controls. Et2 was similarly treated in 1991, and in 1994 the second mercury-arc rectifier was removed in favour of a silicon diode rectifier. During this period, the catenary was renewed as far as the intermediate station of Gnas.

In the period between 1992 and 2002 both the motorbahnwaggen x51 and the goods loco, E41, were equipped for radio remote-control working, and x51 was also provided with a remotely-equipped hydraulic crane. In 2004 the original trailer, EB22, has been repaired for excursion use. ET1 and 2 were built in 1930 by Grazer Wagonfabrik, and seat 58 people. E41 was built in the same year by AEG, and like the railcars, is a Bo-Bo vehicle. The line leaves the junction station of Feldbach in an easterly direction, before turning south through the town, and then generally south-easterly as far as Gnass. The line then turns eastweards towards Katzendorf, making a northerly loop via Hofstoltten to the terminus at Bad Gleichenberg.

The standard gauge line, 21.2 km long, has 82 road crossings on its’ length, and because of the twisting nature of the route, the maximum speed is 40 km/h. There are twelve halts and stations on the branch, with the thirteenth station at Feldbach being shared with the Federal Railway.

Forestry products and the products of the mining industry in the area continue to be important to the railway, providing much-needed goods traffic to the line. The passenger service is sparse, consisting of three return services during daylight hours, with an extra early morning service for school children.