Exhibit 99.1

UNS ENERGY REPORTS SECOND QUARTER 2012 EARNINGS,

MAINTAINS 2012 EARNINGS GUIDANCE RANGE

Tucson, Ariz. – UNS Energy Corporation (NYSE: UNS) today reported second quarter 2012 net income of $26.3 million, or $0.64 per share of common stock on a fully-diluted basis, compared with net income of $28.6 million, or $0.71 per diluted share in the same period last year. TEP reported net income of $21.9 million for the second quarter of 2012, 13 percent below net income of $25.2 million in the second quarter of 2011.

“Through the first half of the year, our financial results are tracking closely with our forecast,” said Paul Bonavia, UNS Energy’s Chairman and Chief Executive Officer. “We knew that 2012 would be a challenging year as TEP’s current electric rates are based on costs and infrastructure investments from 2006. Despite this challenge, our operating performance is strong. We remain committed to containing costs while serving our customers safely and reliably.”

TEP is in the final year of a base rate freeze that was approved in November 2008 by the Arizona Corporation Commission (ACC) as part of a settlement agreement. The settlement precluded TEP from filing a rate case application for new rates prior to June 30, 2012. On July 2, 2012, TEP submitted a rate application with the ACC requesting an increase in non-fuel base rates of $127.8 million or 15 percent over adjusted test year 2011 revenues. TEP requested that new rates be in place no later than August 1, 2013. This is consistent with the agreement among the parties to the 2008 settlement to use best efforts to implement new rates no later than 13 months from the date TEP files a rate application.

“The rate proposal filed by TEP earlier this month is designed to align customer rates with our current cost structure. Our application also contains proposals to reform rates in order to balance the ACC’s renewable energy and energy efficiency requirements with TEP’s opportunity to earn a fair return on investment,” Bonavia said.

Tucson Electric Power

Retail kWh Sales and Revenues

TEP’s retail kWh sales increased by 4.6 percent in the second quarter, due in part to a 45.1 percent increase in cooling degree days compared with the second quarter of 2011. The increase in retail sales volumes led to a $7.3 million, or 5.3 percent, increase in TEP’s retail margin revenues compared with the second quarter of 2011.

Long-Term Wholesale Revenues

As expected, TEP did not record any margin in the second quarter of 2012 on long-term wholesale kWh sales, compared with $4.0 million in the second quarter of 2011. The decrease reflects a pricing change that occurred in June 2011 related to TEP’s largest wholesale sales contract.

Other Operating Expenses

TEP’s base O&M expense was $3.0 million higher than the second quarter of 2011 due in part to planned generating plant maintenance outages. Base O&M excludes costs directly offset by customer surcharges and third-party reimbursements. In the second quarter of 2012, depreciation and amortization expense increased by $3.4 million as a result of additional plant-in-service compared with the same period last year.

Year-to-Date Results

In the first six months of 2012, TEP reported net income of $20.4 million compared with net income of $29.9 million in the same period last year. That decrease was due to the anticipated decline in long-term wholesale margin revenues and higher depreciation expense. Those factors were partially offset by an increase in retail margin revenues.

UNS Gas

UNS Gas reported net income of less than $0.1 million in the second quarter of 2012 compared with net income of $0.4 million in the second quarter of 2011.

UNS Electric

UNS Electric reported net income of $4.5 million in the second quarter of 2012 compared with $3.9 million in the second quarter of 2011. The increase resulted from higher kWh sales to residential and commercial customers. Cooling degree days in UNS Electric’s service territory were 29.8% higher than the second quarter of 2011.

Seasonality of Earnings

The net income and results of operations of TEP as well as of UNS Gas and UNS Electric – operating subsidiaries of UniSource Energy Services (UES) – are seasonal in nature. TEP and UNS Electric typically record the majority of their net income during the second and third quarters when hot weather contributes to higher energy consumption. TEP’s retail rates, which include higher charges for higher levels of energy use, also shift a larger share of the company’s earnings into those periods.

Energy demand from UNS Gas customers typically peaks during the winter. Accordingly, UNS Gas typically records the majority of its net income during the first and fourth quarters.

2

Net Income and Earnings Per Share Summary

UNS Energy believes the presentation of TEP, UNS Gas and UNS Electric net income or loss on a per basic UNS Energy share basis (which are non-GAAP financial measures) provides useful information to investors by disclosing the results of operations of its business segments on a basis consistent with UNS Energy’s reported earnings or losses.

Conference Call and Webcast

The company will host a conference call on Monday, July 30 at 11:00 a.m. ET to discuss the financial results and outlook. To participate in the call, please dial in 5 to 10 minutes prior to the start time.

Dial-in number: (877) 582-0446

Reference code: 13237677

The conference call also can be heard live online at uns.com. The webcast will be available for replay for seven days.

3

Replay number: (855) 859-2056

Reference code: 13237677

In conjunction with this earnings announcement, UNS Energy has provided detailed information on its performance during the second quarter of 2012. These materials have been filed with the Securities and Exchange Commission and are also available at uns.com.

UNS Energy is a Tucson, Arizona-based company with consolidated assets of approximately $4 billion. UNS Energy’s primary subsidiaries include Tucson Electric Power, which serves more than 404,000 customers in southern Arizona, and UniSource Energy Services, provider of natural gas and electric service for about 240,000 customers in northern and southern Arizona.

Visit uns.com for more information about UNS Energy and its subsidiaries.

This release contains forward-looking information that involves risks and uncertainties, including factors that could affect UNS Energy’s ability to reach the 2012 earnings guidance. These risks and uncertainties include, but are not limited to: state and federal regulatory and legislative decisions and actions; regional economic and market conditions, which could affect customer growth and energy usage; weather variations affecting energy usage; the cost of debt and equity capital and access to capital markets; the performance of the stock market and changing interest rate environment, which affect the value of the company’s pension and other postretirement benefit plan assets and the related contribution requirements and expense; unexpected increases in O&M expense; resolution of pending litigation matters; changes in accounting standards; changes in critical accounting estimates; changes to long-term contracts; the cost of fuel and power supplies; performance of TEP’s generating plants; and other factors listed in UNS Energy’s Form 10-K and 10-Q filings with the Securities and Exchange Commission. The preceding factors may cause future results to differ materially from outcomes currently expected by UNS Energy.

4

UNS ENERGY 2012 RESULTS

N/M—Not Meaningful

Reclassifications have been made to prior periods to conform to the current period's presentation.

5

UNS ENERGY 2012 RESULTS

N/M—Not Meaningful

Reclassifications have been made to prior periods to conform to the current period's presentation.

6

TUCSON ELECTRIC POWER COMPANY 2012 RESULTS

N/M—Not Meaningful

Reclassifications have been made to prior periods to conform to the current period's presentation.

7

TUCSON ELECTRIC POWER COMPANY 2012 RESULTS