NEWS

Vancouver, British Columbia – May 14, 2015, 2015 – NioCorp Developments Ltd. (“NioCorp” or the “Company”) (TSX: NBOTCQX: NIOBFFSE: BR3) is pleased to announce it has been named to the 2015 OTCQX® Best 50, a ranking of the 50 top performing companies traded on the OTCQX Best Marketplace last year.  Of the Best 50, Niocorp ranked #2 overall.

The OTCQX Best 50 is the first ever annual ranking of strong performing U.S. and international companies traded on the OTCQX marketplace.  The ranking is calculated based on an equal weighting of one-year share price performance and average daily dollar volume growth in the previous calendar year.  All companies in the 2015 OTCQX Best 50 were traded on OTCQX on December 31, 2014.

“NioCorp is proud to have been ranked as the number two company in the OTCQX Top 50. Our management team is committed to being a top performing company and delivering the best performance possible for our shareholders through hard work, dedication and superior execution. We would like to thank the OTCQX for this honor.”

For the complete 2015 OTCQX Best 50 ranking, visit http://www.otcmarkets.com/content/doc/2015-OTCQX-Best-50.pdf.

The OTCQX Best Marketplace offers the best informed and most efficient trading for established, investor-focused U.S. and international companies.  To qualify for OTCQX, companies must meet high financial standards, demonstrate compliance with U.S. securities laws, be current in their disclosure and be sponsored by a professional third-party advisor.  OTCQX companies are distinguished by the excellence of their operations and diligence with which they convey their qualifications.

About the Company:  NioCorp is developing the only primary niobium deposit known to be under development in the U.S., and the highest grade undeveloped niobium deposit in North America, located near Elk Creek, Nebraska.  The Company has filed a resource estimate completed in accordance with NI43-101 reporting standards with an effective date of February 20, 2015 reporting an Indicated Resource of 80.5 million tonnes grading 0.71% Nb2O5, 2.68% TiO2 and 72 ppm Sc and an Inferred Resource of 99.6 million tonnes grading 0.56% Nb2O5, 2.31% TiO2 and 63 ppm Sc (at a 0.3% Nb2O5 cutoff grade).  Niobium is mainly used in the form of Ferro-Niobium to produce HSLA (High Strength, Low Alloy) steel, which is a lighter, stronger steel used in automotive, structural and pipeline applications.  The U.S. imports 100% of its niobium needs.  Titanium in the form of an oxide is used extensively as a pigment in paints, plastics and papers.  As a metal, titanium is used in aerospace applications, armor, chemical processing applications, marine hardware applications, medical implants, power generation and in sporting goods. Scandium is used in solid oxide fuel cells (SOFCs) and aluminum-scandium alloys, as well as in ceramics, electronics, lasers and lighting applications.

For further information, contact the Company at (604) 568-7365 or at www.NioCorp.com

ON BEHALF OF THE BOARD

“Peter Dickie”

Director and President

Neither TSX nor its Regulation Services Provider (as that term is defined in the policies of the TSX) accepts responsibility for the adequacy or accuracy of this release.