Press Release

PalmSource Schedules Fourth Quarter & Fiscal Year End 2004 Results & Conference Call on June 24

SUNNYVALE, Calif.— June 3, 2004 — PalmSource, Inc. (NASDAQ: PSRC) provider of Palm OS™, a leading operating system powering next generation mobile devices and smartphones, will release results for the fourth quarter and fiscal year end 2004 results on Thursday, June 24th, 2004 after market close. David Nagel, president & chief executive officer and Al Wood, chief financial officer, will discuss fourth quarter and fiscal 2004 year end results and business outlook on a conference call scheduled for 5:00 PM Eastern Daylight Time / 2:00 PM Pacific Daylight Time that same day.

A live and archived Web cast of this call can be accessed at PalmSource's web site at www.palmsource.com/about/ir.html. The Web cast is also being distributed over CCBN's Investor Distribution Network to both institutional and individual investors through CCBN's individual investor center at www.companyboardroom.comand by visiting any of the investor sites in CCBN's Individual Investor Network or via CCBN's password-protected event management site, StreetEvents (www.streetevents.com).

About PalmSource
PalmSource, Inc. is the company behind Palm OS, a leading operating system powering mobile information devices. Approximately 33 million Palm Powered handhelds and smartphones have been sold to date worldwide. Industry leaders Aceeca, AlphaSmart, Fossil, Founder Technology, Garmin, GSL, HuneTec, Kyocera, Lenovo, palmOne, PerComm, Samsung, Sony, Symbol Technologies and Tapwave license Palm OS to create diverse mobile devices that meet unique customer needs. Palm OS has given rise to a large community of users, enterprises, developers and manufacturers, who together make up the Palm Powered Economy. More information about PalmSource is available at www.palmsource.com, www.palmsource.co.uk, www.palmsource.fr, www.palmsource.de and www.palmsource.com.cn.

Palm, Palm OS, PalmSource, palmOne and Palm Powered are trademarks of Palm Trademark Holding Company, LLC.