Google will unveil a mobile payment system on Thursday, May 26.

Two months after Google's test phase report in March, the long-waited mobile payment system will run on the Android operating system, and is expected to first be available for the Sprint Nexus S phones. Google teamed up with MasterCard and Citigroup to develop the system. 

The rumors hint the launching of phones equipped with NFC chips, which marks the first payment system ever entirely on phone. 

Google is expected to present an action plan and milestones, or simultaneously release a new or modified Android-Sprint phone.

Google, Sprint and MasterCard declined to comment on the release. Google will hold a press release this week, and the upcoming weekend All Things Digital Conference may be a stage for Google's presentation of NFC-enabled android phones.

In mid-2012, a joint venture between AT&T, Verizon and T-Mobile is expected to introduce Isis, an electronic wallet of NFC-enabled phones.

Despite the competition among a growing number of mobile operators, banks, technology companies and card processing networks, Google and Sprint will be the first in entering the U.S. mobile payment market, fueled by Google's ambitions proven in the past. 

Among the rumors is Apple's plan to include a NFC reader in a new version of iPhone. However, according to a report released in the UK, iPhone 4S, a slight upgrade from the last iPhone 4, will be released first. 

The first to participate in NFC checkout will be Macy's, American Eagle and Subway, according to insiders of the Wall Street Journal. 

New York and San Francisco will be the first to test the mobile payment, followed by Los Angeles, Chicago and Washington D.C.