The Serajoedal Stoomtram Maatschappij (SDS or SDSM, Dutch for Serayu Valley Steam Tram Company, Indonesian also Perusahaan Trem Uap Lembah Serayu) was a railway company, whose route followed the Serayu Valley and connected Maos via Patikraja, Purwokerto, Sokaraja, Purbalingga, Klampok, Mandiraja and Banjarnegara with Wonosobo on 142 kilometers of rail network.

This company are the pioneer of railway development in Banyumas Regent, even before Staatsspoorwegen exist in earlier 1900's.

Repelaer van Driel had received concessions for the construction and operation of a steam railway in 1893 and 1894.

The construction of the track cost 1,500,000 guilders, financed by the Financiele Maaatscappij van Nijverheidsondernemingen in Ned.

The assets, which had been formerly owned by the SDS and later the PT Kereta Api Indonesia belonged to the Department of Transportation of the Republic of Indonesia from the 1980s to regional autonomy in 2001 and to the Transportation Department of the province of Central Java from 2001 to 2006 .