Unite is to ballot members working for International Consultants on Targeted Security (ICTS), which provides the baggage screening process for Trans-Atlantic and European flights for airlines including Emirates, American Airlines, Virgin and Thomas Cook.
The union said ICTS workers at Glasgow Airport should be paid the same as those at Edinburgh Airport.
It claimed a recent pay offer would have left workers in Glasgow, earning nine pence an hour less than those in the Scottish capital.
Unite said members could take industrial action next month and all major airlines would be affected.
Regional officer Pat McIlvogue said: “Unite has continually attempted to seek remedy with ICTS management to avoid a dispute. These requests have been met with either no response or delaying tactics.
“ICTS is a strong and profitable multi-national company.
“There can be no doubt that it can afford to provide a decent pay rise for its employees at Glasgow Airport in line with rates and conditions at Edinburgh Airport.
“We believe it is reasonable that Glasgow Airport ICTS workers should be treated no differently from fellow workers at Edinburgh Airport doing exactly the same job. This is a simple question of fairness.
“ICTS has agreed to Acas talks on 9 August and Unite remains hopeful that a remedy can be found before then.
“However, ICTS management should be under no illusions of the determination of our members to get what they rightfully deserve, which is parity with their colleagues in Edinburgh.”
A Glasgow Airport spokesman said: “We are aware of the planned ballot and are liaising with ICTS in regards to their contingency plans should they be required.”