The UK's South Eastern Railway will start the limited 140mph high-speed 'preview' service between Ashford International, Ebbsfleet International and St Pancras International on 29 June.
The preview service on High Speed 1 will help the company get UK passengers' feedback on travel experience and continue testing, training and improve services.
High-speed services will reduce the journey times from Ashford International to London by 37 minutes and from Ebbsfleet International by 17 minutes.
The cost of a single high-speed mainline preview fare from Ashford International to St Pancras has increased to £26.60 from £22.20, but first class ticket holders are able to travel for no extra cost.
These new rates are applicable to preview services only.
The UK's first high-speed service will be fully introduced on 13 December.