They are both possible. I would normally use "working hours", but maybe 'work-hours' or 'work hours', at different times, different circumstances. Usually with a hyphen. "My working hours are from 7am to 7pm."

How do you say your working hours?

Generally when someone asks you about your working hours, one should mention the start time and then mention the time you head back home. Example – I start work at 11 am and the I am done by 8 pm.

What working hours mean?

working hours. noun [ plural ] HR, WORKPLACE. the amount of time someone spends at work during a day: Personal use of the internet by office workers is costing British firms 233 million working hours a month.