The bank said the move was to provide greater flexibility in financing for exports, and followed the Organisation of Economic Cooperation and Development (OECD) recently increasing its term for repayment up to 18 years.
In addition to hydro power, the new repayment terms are available to other renewable energy projects as well as water and nuclear schemes.
In a statement, US Exim Bank chairman and president, Fred P Hochberg, said: 'The new terms provide incentives and will help to make these projects more competitive and enable us to support more American jobs in these industries.'
The new terms are available for transactions approved with effect from 1 July, and will be reviewed again in 2013.
The US Exim Bank established its Office of Renewable Energy and Environmental Export two years ago.
