The NS 1700 was a series of express steam locomotives of Nederlandse Spoorwegen and its predecessor Maatschappij tot Exploitatie van Staatsspoorwegen (SS).

The first 125 locomotives were built by Beyer, Peacock & Company of Manchester, England and delivered to the SS between 1899 and 1906 with numbers 801–925.

After experiences with other superheated locomotives showing the advantage of this, the SS decided to also test a superheater on the series 800.

After the first locomotives were converted by the workshop in Tilburg, the NS needed help of Werkspoor in Amsterdam and Utrecht.

Due to the financial crisis, as a result of which NS also had to revise its spending pattern, the serial conversion of 1700s with a superheater came to an end after one hundred locomotives.

Plans to implement this for all remaining locomotives not yet fitted with superheater failed due to costs that were deemed too high.

To prevent Tilburg workshop personnel from being put to work in Germany during the Second World War, two more locomotives were fitted with a superheater.