Southeastern, which provides rail services in the area, says it will mean that the vast majority of its trains will not run be running.
The ASLEF union is also due to take industrial action on Saturday (July 30), with Southeastern saying there will be no services at all running on that day.
The rail company is strongly advising passengers not to travel either on Wednesday or Saturday, while further disruption is expected on the days immediately after the industrial action.
All but 44 stations on Southeastern’s network will be closed today, with only the London-Sevenoaks and Dartford lines remaining open within London and running a very limited service.
It is the second strike arranged by RMT, who led three days of walk outs last month.
Further walkouts are planned for next month when the RMT will again strike on Thursday, August 18 and Saturday, August 20.
The industrial action means there will be no trains serving most of Kent, including Tonbridge, Tunbridge Wells, Maidstone, Thanet, Canterbury, Folkestone and Dover, with Highspeed trains only running between London St Pancras and Ashford.
No rail replacement buses or taxis will be available and the strike is likely to cause disruption on Thursday when services are meant to resume.
Robert Mansfield from Tonbridge Line Commuters (TLC), which campaigns for a better service for passengers in the area, said: “We are disappointed that Southeastern are unable to run any services in Tonbridge, leaving one of Kent’s busiest stations empty.”
He added: “The days of the strikes reflect how rail travel patterns have changed. Key workers and leisure travellers are the most vulnerable groups to this strike. Whilst many people can work from home, you can’t pick fruit, visit the beach or see a live show from home.”