The outgoing owner of a Melbourne bus company has rewarded staff with cash gifts totalling tens of millions of dollars.

When Ken Grenda sold his bus company for $400 million, he wanted to thank his almost 2,000 staff members for their hard work.

The amount given to each staff member is based on their length of service.

Some workers received more than $100,000 each.

The owner's son and the company's managing director, Scott Grenda, says his father was sad to sell the business and wanted to express his gratitude to staff.

"You know we've got employees that stretch over 40 years so it is a pretty nice thing to do," he said.

One bus driver, John, says Ken Grenda has been a great man to work for.

"He is a generous person and a true gentleman," he told ABC local radio.

The company has been bought by transport operator Ventura.