Launched in 2008, the start up offers a single-click billing and payment service for Web-based transactions conducted on mobile phones, including Android and iPhone devices

Citi Ventures' funding follows its sponsorship last year of Billing Revolution's Single-Click Checkout Android app. The bank's active investment in the firm follows the completion of a $6.6 million Series B funding round two weeks ago that was led by DCM and SK Telecom Ventures.

The Citi Ventures unit was recently moved from New York to Silicon Valley, in an effort to get loser to groundfloor buzz on innovation in payments. Citi Global Enterprise Payments was launched four months later in October last year, combining the bank's transaction banking and cards businesses in an initiative to provide services in the corporate-to-consumer market.

Dickson Chu, recruited from Paypal to act as a managing director in the Global Enterprise Payments group, says of the Billing Revolution investment: "There is a lot of activity in the mobile payments space, but Billing Revolution's platform and approach are truly innovative, and the company has the potential to be a game changer. That is one of the reasons why Citi decided to become both a sponsor and investor."