Google is buying US radio advertising firm dMarc Broadcasting for an upfront payment of $102m (£58m), rising to a possible $1.14bn by 2009.
Google is branching out yet again
The internet search giant said it expected to integrate dMarc technology to allow its current advertisers to advertise on radio through Google.
The deal is just the latest investment by Google. Last month it paid $1bn for a 5% stake in the AOL website.
Google has been steadily branching out from its core web search business.
Over the past few years it has moved further into e-commerce, such as launching its own video rental scheme, in addition to introducing e-mail accounts, news and map information and other services.
Last month it also reached an out-of-court settlement with Microsoft over its appointment of a former Microsoft senior member of staff in China.
The deal for California-based dMarc could rise to $1.14bn, depending upon whether a number of undisclosed performance targets are met.
"Google is committed to exploring new ways to extend targeted, measurable advertising to other forms of media," said Tim Armstrong, Google's vice-president for advertising sales.
Google previously bought advertising in print magazines before selling on chunks of the space to its online advertisers.