The RMT rail union said the action was planned for September 30th and October 1st following summer travel disruptions that forced workers to deal with thousands of angry customer complaints.
“The conditions at St Pancras have been simply appalling over the summer with dangerous levels of overcrowding on the concourse as services plunge into meltdown on the cusp of the busiest part of the year,” RMT general secretary Mick Cash said.
An RMT statement said the dispute was “over shocking and dangerous working conditions resulting from repeated service failures and breakdowns.”
There was no immediate response from Eurostar.
St Pancras station provides fast rails service to Paris and Brussels as well as Amsterdam and two other locations in France.