Sony said the addition of the public-domain books from Google brings the number of titles in the Sony eBook Store to more than 600,000, more than double the 240,000 available for rival Amazon's Kindle.
The books from Google were all written more than 80 years ago, however. Amazon for its part prides itself on offering the latest releases for the Kindle, including most of The New York Times bestsellers.
The books offered to Sony by Google include classics such as Mark Twain's 'A Connecticut Yankee in King Arthur's Court' and Jane Austen's 'Sense and Sensibility.'
'Working with Google, we can offer book lovers another avenue for free books,' Steve Haber, president of Sony's digital reading business division, said in a statement.
Google has been scanning millions of books in the world's libraries as part of its Google Book Search project.
Adam Smith, a product management director at Google, said 'We founded Google Book Search on the premise that anyone, anywhere, anytime should have the tools to explore the great works of history and culture.'
'We believe in an open platform for accessing and reading books, and we're excited to partner with Sony to help bring these public domain books to more people,' he said.
Sony sells two models of its reader — the PRS-505 for 300 dollars and the PRS-700 for 350 dollars.
Amazon's Kindle sells for 359 dollars. The Seattle-based online retail giant released a new model the Kindle last month.
Google last month announced plans to make its vast online library of more than 1.5 million public domain books available for mobile phones such as the Apple iPhone or T-Mobile G1, which is powered by Google's Android software.
