The Shadow Chancellor will visit the SSI steel plant, which is set to close with the loss of up to 1,700 jobs.
John McDonnell told ITV News Tyne Tees' Political Correspondent Paul Brand, he would be making a trip up to Redcar "on Monday if not before".
He has said he plans to put "maximum pressure" on the Government to do more to help the stricken plant:
The factory is being shut down after Thai owner SSI said it had no other choice because of plummeting steel prices.
New figures show nearly a thousand people who worked for companies that supplied the SSI Redcar have been made redundant since it closed.
A new programme to help find jobs for steelworkers hit by a wave of redundancies will be chaired by the former deputy prime minister.
More than 800 jobs have been lost at Tees Valley firms that supplied the SSI steelworks in Redcar.