No trains will run across the "vast majority" of Govia Thameslink services next Tuesday.
January 30 will see industrial action by the ASLEF Union cancel most of the provider's services.
Govia Thameslink operates Southern, Gatwick Express, Thameslink and Great Northern trains, serving much of Hertfordshire.
A limited shuttle service between London Victoria and Gatwick Airport will run on the day, along with a shuttle between Luton, Luton Airport Parkway and London St Pancras.
A limited shuttle service will also run between London King’s Cross and Cambridge.
Due to a nationwide overtime ban, an amended timetable will also be in place from January 29 until February 6.
Jenny Saunders, Govia Thameslink’s customer services director, said: “We’re very sorry about the impact this industrial action will have on our customers.
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"With no trains on the majority of our network on Tuesday, January 30, we’re asking people to plan ahead and use alternative travel options.
“Whilst there will be trains running on either side of the strike day, the nationwide overtime ban means we are only able to run an amended timetable with fewer trains.
"With other train operators affected on different days, we’re asking customers to check their entire journey each day from Monday, January 29, until Tuesday, February 6.”
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