July 31, 2008

UniSource Energy to Discuss Second Quarter 2008 Financial Results

UniSource Energy Corp. (NYSE: UNS) officials will discuss the company's 2008 second quarter financial results during a conference call hosted by James S. Pignatelli, UniSource Energy chairman, president and chief executive officer.

UniSource Energy expects to release its 2008 second quarter financial results on Wednesday, August 6, after the market closes. That release will be available online at uns.com. The conference call is scheduled for Thursday, August 7, at 12 p.m. EDT.

Telephone Access

To listen to the live conference call, dial 877-582-0446 five to 10 minutes prior to the event and reference confirmation code 58773656. A telephone replay will be available for seven days starting August 7. To listen to the replay, dial 800-642-1687 and reference confirmation code 58773656.

Internet Access

A live audio-only webcast of the presentation is available through a link at uns.com. Listeners are encouraged to visit the website at least 30 minutes before the presentation to register, download and install any necessary audio software. A recording of the webcast will be available for 30 days through a link at uns.com.

UniSource Energy's primary subsidiaries include Tucson Electric Power Company, which serves nearly 400,000 customers in southern Arizona; UniSource Energy Services, provider of natural gas and electric service for about 236,000 customers in northern and southern Arizona; and Millennium Energy Holdings, parent company of UniSource Energy's unregulated energy businesses. For more information about UniSource Energy and its subsidiaries, visit uns.com.