A reduced working week of 51 hours, from 54, is expected to go on trial by the end of the year after more than half of the firefighters supported the move in a survey.
The fire department said it would submit the proposal to the security and civil service bureaus, and launch a trial scheme by end of this year. But some firefighters were unhappy because it fell short of their demand for a 48-hour week.
Staffs General Association chairman Lee Tak-kei said its members were disappointed that there was no concrete timetable for the 48-hour week, which they had spent 23 years battling for.
"From the beginning till now, we have been fighting for a reduction to 48 [hours per week]," said Lee.
"The 51[-hour proposal] can only be transitional."
If the trial on the 51-hour week is a success, further reductions could be discussed.
A successful trial would mean that no costs and additional manpower were required and that the level of service had not been reduced.
"During the trial period, if everything goes smoothly and the administration accepts the proposal … then we will set up another working group to further explore the flexibility of reducing the work week to 48 hours," said James Ng Kuen-chi, the assistant director of fire services.
Under the 51-hour proposal, the number of firefighters sent to a category one fire - the least severe of the five categories - would be cut from 22 to 20.