Similar action last year brought buses to a standstill
Staff members at First Bus in Aberdeen have voted in favour of strike action over pay, with about 70% of those who voted backing the move.
The T&G Unite union had recommended a vote in favour of industrial action this summer.
First Bus management called on the union to "sit down with us to agree a way forward" after the vote.
Similar action last year, before a deal, brought buses to a standstill. No strike dates have yet been announced.
Duncan Cameron, operations director at First in Aberdeen, said: "The people of Aberdeen will neither understand nor forgive the union for the disruption that would be caused by a strike."
The company said no rise was available unless staff agreed changes to their terms and conditions.
The union's regional organiser, Tommy Campbell, said they were still willing to negotiate.