Sydney Ferries could be privatised within a year, the NSW government says.

Transport Minister David Campbell called on Wednesday for expressions of interest from the private sector to run Sydney Harbour's ferry service.

"The private sector have said they can do better, (there is an) opportunity now for them to put their money where their mouth is," Mr Campbell told reporters in Sydney.

He said the government would be looking for the best proposal, but not necessarily the cheapest.

"We'll be looking to get the best service levels for commuters ... in terms of timetable, in terms of operation, in terms of on-time running," Mr Campbell said.