Mobile banking is growing so fast that a year from now Commonwealth Bank expects more customers to access its Netbank service from mobile devices rather than from computers. At present, mobile access represents 35 per cent of all Netbank interactions - up from two per cent just two years ago.Andrew Murrell, general manager of channel marketing at CBA, said that since the launch of its first mobile application, in 2008, there had been 2.2 million mobile app downloads in total, and that the bank had now moved to a quarterly application refresh cycle.Although the first app was released in 2008, it was not updated until 2010 and had been left "languishing" in the Apple iTunes store with a scant two-and-a-half star user rating. "That was negligent of us," he acknowledged.Asked when the next refresh of the Kaching payments app might appear - the present version is now more than three months old - Mr Murrell said there would be announcements shortly, adding that the Android version of the app was currently in testing.A payments app, which allows contactless payment when coupled with an NFC (near field communications chip)-enabled iCarte case on an iPhone, Kaching is an important payments weapon for the bank.Murrell said: "Payments are going to become a battlefield, not just... [among the] banks but the likes of Google and PayPal [too]. That's why we are investing in mobile."Murrell was speaking at a financial services event hosted last Thursday by Joob, the mobile division of Jade Software, which provides the middleware used to develop mobile systems.He said that in the future the bank would continue to extend its social network links, and would also introduce elements of gamification - essentially, allow people to play games on their phone or tablet and be rewarded for doing so - onto its mobile platforms. The aim is to entice more users to use the bank's systems.