May 17, 2012 
Excelsior Mining Corp. (TSX-V: MIN) (Frankfurt: 3XS) (OTCQX: EXMGF) (�Excelsior� or �the Company�) is pleased to provide an update on its on-going 2012 drilling program at the Gunnison Copper Project, located in southern Arizona. The program is designed to acquire geological, metallurgical and hydrological data with the aim of completing a Pre-Feasibility Study on Gunnison by the end of 2012.

�We�re pleased with the progress of our 2012 program,� stated Stephen Twyerould, President and CEO of Excelsior. �The program has been designed to advance the project in a number of areas and the timely acquisition of this data will enable us to achieve our goal of completing the Gunnison Pre-Feasibility Study by year�s end.�

2012 Work Program Details

Metallurgy
The metallurgical component of three holes, totaling 3,178 feet (968.7 metres) has been completed with samples sent to Metcon Research of Tucson, AZ for analysis. This analysis will involve running in-situ recovery simulation tests, conducted to support previous results indicating favorable metallurgical conditions.

Resource Definition and Upgrade
The geological component of the program, designed to upgrade and expand the existing mineral resource, is approximately 50% complete with the first set of assay results expected by June. Approximately 19 holes, totaling 24,000 feet (7,316 metres) are planned for this phase of the program with a new resource estimate anticipated for later in the year.

Hydrology
Drilling has begun on the hydrological test holes, which constitute the third and final component of this year�s drilling. Up to 10 hydrological test wells are planned with the goal of producing an initial hydrological model. Monitoring and observation wells will also be added later this year. Data collected from these wells will be required for the permitting process as the project continues to advance.

The data acquired from this current drilling program will be combined with the existing dataset for use in the Pre-Feasibility Study to optimize wellfield design, leaching solution composition, as well as provide critical information for groundwater quality control and ultimately, project reclamation, all of which will be essential as the project moves forward. The Pre-Feasibility Study is scheduled for completion in December. This key study will provide wellfield design parameters, annual copper production rates and a new financial model. Drilling is being carried out by B-J Drilling Company, Inc. of Benson, AZ and Godbe Drilling LLC of Montrose CO. Downhole geophysical surveys are being conducted by Southwest Exploration Services, LLC of Chandler, AZ. Hydrologic testing is being conducted by the engineering and environment firm Haley & Aldrich, Inc.

Project Summary

The Gunnison Copper Project is located in a remote section of Cochise County in southeastern Arizona. The focus of the project is the North Star deposit, which currently has a total Indicated mineral resource of 3.21 billion pounds of oxide copper (511 M tons at 0.31%) and an Inferred mineral resource of 0.88 billion pounds of oxide copper (159 M tons at 0.28%). This oxide mineral resource has the potential to be mined using in-situ recovery methods. Mineral resources that are not mineral reserves do not have demonstrated economic viability.

About Excelsior

Excelsior is an exploration company with a copper project located within the Copper Porphyry Belt of Arizona.  The Gunnison Copper Project is located close to the required infrastructure and its oxide resource has the potential to be mined using in-situ recovery methods.  The Excelsior team consists of experienced professionals with proven track records of advancing projects towards production.

Excelsior�s exploration work on the Gunnison Property is supervised by Dr. Stephen Twyerould, Fellow of AUSIMM, President and CEO of Excelsior, and a Qualified Person as defined by NI 43-101. Dr. Twyerould has reviewed and approved the technical information disclosed in this news release.

Further details about Excelsior can be found at: http://www.excelsiormining.com.  Further information about the Gunnison Copper Project can be found in the technical report filed on SEDAR at www.sedar.com entitled: �Gunnison Copper Project Preliminary Economic Assessment, NI 43-101 Technical Report� dated November 18, 2011.

For further information regarding this press release, please contact:

Excelsior Mining Corp.
Concord Place, Suite 300, 2999 North 44th Street, Phoenix, AZ, 85018.

JJ Jennex, Vice President, Corporate Affairs
T: 604-681-8030 x240
E: info@excelsiormining.com
www.excelsiormining.com


Cautionary Note Regarding Forward-Looking Information
This news release contains "forward-looking information" concerning anticipated developments and events that may occur in the future. Forward looking information contained in this news release includes, but is not limited to, statements with respect to: (i) the estimation of inferred and indicated mineral resources; (ii) success of exploration activities; (iii) statements about the details of the 2012 work program; (iv) the completion of a pre-feasibility study; (v) the future exploration on and the development of the Gunnison Project; (vi) the permitting process and (vii)  the ability to mine Gunnison using in-situ recovery mining techniques are forward-looking statements.

In certain cases, forward-looking information can be identified by the use of words such as "plans", "expects" or "does not expect", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates" or "does not anticipate", or "believes", or variations of such words and phrases or state that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur" or "be achieved" suggesting future outcomes, or other expectations, beliefs, plans, objectives, assumptions, intentions or statements about future events or performance. Forward-looking information contained in this news release is based on certain factors and assumptions regarding, among other things, the estimation of mineral resources, the realization of resource estimates, copper and other metal prices, the timing and amount of future exploration and development expenditures, the estimation of initial and sustaining capital requirements, the estimation of labour and operating costs, the availability of necessary financing and materials to continue to explore and develop the Gunnison Project in the short and long-term, the progress of exploration and development activities, the receipt of necessary regulatory approvals, the completion of the environmental assessment process, the estimation of insurance coverage, and assumptions with respect to currency fluctuations, environmental risks, title disputes or claims, and other similar matters. While the Company considers these assumptions to be reasonable based on information currently available to it, they may prove to be incorrect.

Forward looking information involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by the forward-looking information. Such factors include risks inherent in the exploration and development of mineral deposits, including risks relating to changes in project parameters as plans continue to be redefined including the possibility that mining operations may not commence at the Gunnison Project, risks relating to variations in mineral resources, grade or recovery rates resulting from current exploration and development activities, risks relating to the ability to access infrastructure, risks relating to changes in copper and other commodity prices and the worldwide demand for and supply of copper and related products, risks related to increased competition in the market for copper and related products and in the mining industry generally, risks related to current global financial conditions, uncertainties inherent in the estimation of mineral resources, access and supply risks, reliance on key personnel, operational risks inherent in the conduct of mining activities, including the risk of accidents, labour disputes, increases in capital and operating costs and the risk of delays or increased costs that might be encountered during the development process, regulatory risks, including risks relating to the acquisition of the necessary licenses and permits, financing, capitalization and liquidity risks, including the risk that the financing necessary to fund the exploration and development activities at the Gunnison Project may not be available on satisfactory terms, or at all, risks related to disputes concerning property titles and interest, environmental risks and the additional risks identified in the �Risk Factors� section of the Company�s Annual Information Form for the most recently completed financial year or other reports and filings with applicable Canadian securities regulations.

Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward-looking information, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. There can be no assurance that forward-looking information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. Accordingly, readers should not place undue reliance on forward-looking information. The forward-looking information is made as of the date of this news release. Readers are cautioned that the foregoing lists of factors are not exhaustive. The forward-looking information contained in this news release is expressly qualified by this cautionary statement. Except as required by applicable securities laws, the Company does not undertake any obligation to publicly update or revise any forward-looking information.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release, and no securities regulatory authority has either approved or disapproved of the contents of this release.