Microsoft is introducing "lightweight" versions of Office applications that can be accessed via any browser over the web.
The move may be seen as a response to Google winning support for its web-based productivity software in some enterprises.
Chris Capossela, Microsoft Business Division senior vice-president, said, "As part of the next release of Office, Microsoft will deliver Office Web applications - lightweight versions of Word, Excel, PowerPoint and OneNote - through a browser.
"With these applications, people can use a browser to create, edit, and collaborate on Office documents. What is great is that this provides a consistent Office experience when and where our customers want it, regardless of whether they are accessing their Office documents through the PC, phone, or browser."
Capossela was keen to stress that the move was not a sudden dash by the firm towards cloud-based computing.
He said, "For more than 10 years, millions of workers have benefited from Microsoft cloud-based services, including Hosted Exchange, Outlook Web Access and Live Meeting. Earlier this year, we announced Microsoft Online, which businesses such as Coca-Cola Enterprises and Blockbuster are using to access Exchange and SharePoint over the Web.
"Last month, more than one million people turned to Office Live Workspace for sharing and collaborating over the internet."
Office Web applications will be delivered to consumers' PCs, phones and other mobile devices through the Office Live, which is a consumer web service with both ad-funded and subscription offerings.
For business customers, Office Web applications will be offered as a hosted subscription service and through existing volume licensing agreements.
A private technology preview of the Office Web applications will be released later this year.