The Internet search giant said mobile versions of the books optimized to be read on a small screen could be read on devices such as the Apple iPhone or T-Mobile G1, which is powered by Google's Android software.
Users can access the mobile version of Google Book by typing in http://books.google.com/m into their iPhone or Android phone web browser.
"We are excited to announce the launch of a mobile version of Google Book Search, opening up over 1.5 million mobile public domain books in the US (and over half a million outside the US) for you to browse," the company said.
Google's announcement comes days before Amazon unveils a new generation version of its popular Kindle electronic book reader. Amazon also said it plans to make its online store of e-books for the Kindle available on mobile phones.
Google will initially only offer non-copyrighted books in the public domain. Amazon, on the other hand, will offer the latest releases and 230,000 titles, including 103 of the 112 current New York Times bestsellers.
