Hollandsche IJzeren Spoorweg-Maatschappij

Infobox Defunct Company
company_name = Hollandse Ijzeren Spoorweg-Maatschappij
company_
fate = Merged with the Maatschappij tot Exploitatie van Staatsspoorwegen
successor = Nederlandse Spoorwegen
foundation = 1837
defunct = 1938
location = Amsterdam, The Netherlands
industry = Rail Transport
key_people =
products =
num_employees =
parent =
subsid = The Hollandsche IJzeren Spoorweg-Maatschappij or HSM ("Hollands Iron Railway-Company") was the first railway company in the Netherlands founded on 8 August 1837 as a private company, starting operation in 1839 with a line between Amsterdam and Haarlem. The company remained operational till 1938, when it merged with the Maatschappij tot Exploitatie van Staatsspoorwegen (SS) to form the Nederlandse Spoorwegen (NS).

The first line constructed was a line connecting Amsterdam with Haarlem, which opened on 20 September 1839. The line was quickly expanded and reached Leiden in 1842, The Hague in 1843 and Rotterdam in 1847. Because this line is the oldest line in the Netherlands, it is now known as the Old Line. This line was originally build to Dutch broad gauge RailGauge|1945mm, but was converted to standard gauge in 1866.

The line started at the Haarlemmerpoort on the westside of Amsterdam, across the street from the company's headquarters and ran to the station Deltse Poort in Rotterdam. Aside from this line, the HSM constructed a number of other rail- and tramways in the Netherlands, mainly in the relatively densely populated Holland, such as the lines to Den Helder and Alkmaar. But the HSM also exploited lines to other regions, such as Utrecht (where it connected to lines of the SS), Zutphen (past cities as Amersfoort and Apeldoorn) and Nijmegen. The HSM even exploited a line to Leeuwarden, which took passengers by boat over the Zuiderzee.

However, economic woes caused by the First World War forced the HSM to start cooperation with the SS to strengthen their economic position. Eventually, this would lead to the formation of the Nederlandse Spoorwegen.