London Underground cleaners are protesting against the introduction of fingerprint recognition machines.
On Thursday, hundreds of workers plan to refuse to cooperate with the clocking-in system after 98% of those who voted in a ballot opted for the action, said the RMT union.
The technology infringed their rights, the union added.
The cleaners - who are employed by Danish firm ISS UK - will continue to sign in manually and by phone.
"We believe this technology infringes on staff civil liberties and the overwhelming vote in favour of action shows our members' strength of feeling on this issue," said Bob Crow, RMT's general secretary.
But Adam Wurf, communications director for ISS UK told the BBC: "With this technology we will be able to guarantee that the member of staff is who they say they are.
"We don't think this is draconian or an infringement of civil liberties; it's about making sure we have the right people - verified and trained - in the right place at the right time."
The row about biometrics - technology that uses unique human features to identify an individual - coincides with the launch of Apple's latest iPhone, which incorporates a fingerprint recognition button.
While fingerprint technology has been around for several years, particularly in PCs designed for business-users, there have been concerns about its reliability.
Some cryptographers have been able to create "spoof" fingerprints using the gelatine found in sweets. Apple aims to avoid this pitfall by scanning "sub-epidermal skin layers".