Sydneysiders will be able to use the one card to pay for tickets on ferries, trains and buses by 2015, the NSW government says.


NSW Transport Minister Gladys Berejiklian said on Sunday the Opal card will be available on all Sydney ferries and some trains in 2013, with buses and light rail to come on line by 2015.


She says the first commuters to have access to the card will be patrons on the Neutral Bay ferry route in a trial of the system from December 7.


"This is something that will change the way we use public transport," Ms Berejiklian told reporters.


"It will be an easy system where commuters simply have to top on and tap off, and it will be like having an e-TAG in your pocket."


She said fares would remain the same during the Neutral Bay trial, while further announcements on charges would be made during the system's roll-out.


The Opal card itself will be free, with public transport users putting money on it in a similar way to the e-TAG for cars.


Ms Berejiklian said a big benefit of the Opal card will be that after eight journeys using it in a given week, all further trips will be free.


She also said there would be a daily travel cap of $15.00 from Monday to Saturday for Opal card customers, with a cap on Sundays of $2.50.


She expected there would be a "few glitches" during the roll-out and said that's why the single card system was being implemented progressively.


"It's a very complex task," she said.


"It will take the next three or four years to finalise."


AAP