NEWS

CENTENNIAL, Colo. – September 17, 2015 – NioCorp Developments Ltd. (“NioCorp” or the “Company”) (TSX: NB, OTCQX: NIOBF, FSE: BR3), is pleased to announce the production of ferroniobium using feed material from the Elk Creek Resource that meets specifications for commercial sale.

NioCorp has retained Kingston Process Metallurgy Inc. (“KPM”) of Kingston, Ontario to conduct a series of pyrometallurgical tests to provide design information for the ferroniobium production process and to generate small quantities of ferroniobium. Testwork conducted in August of 2015 produced a final ferroniobium button that weighed 78 grams. The button was analyzed in KPM’s internal laboratory, as well as at two external laboratories: SGS of Lakefield, Ontario and Actlabs of Ancaster, Ontario. NioCorp then compared the analytical results to a commercial specification for ferroniobium contained in the Company’s offtake agreement with Thyssen Krupp Metallurgical Products GMBH and determined that the specification was met.

“We are extremely pleased with the work completed by the KPM team in order to achieve this important milestone for the Elk Creek project,” said Mark A. Smith, Executive Chairman of NioCorp. “These results are the culmination of our efforts to demonstrate a complete flowsheet for the production of ferroniobium at a laboratory scale, and will be combined with the other elements of our metallurgical development program to advance our plant design to the feasibility level.”

Qualified Persons:

Eric Larochelle, B.Eng of Roche Engineering Inc, a Qualified Person as defined by National Instrument 43-101, is responsible for the Elk Creek hydrometallurgical program and has read and approved the technical information contained in this news release.

Kevan Ford of Great Lakes Metallurgy Ltd., a Qualified Person as defined by National Instrument 43-101, is responsible for the Elk Creek pyrometallurgical program and has read and approved the technical information contained in this news release.

About NioCorp:

NioCorp is developing the Elk Creek Niobium / Scandium / Titanium project in Southeast Nebraska. Niobium is used to produce High Strength, Low Alloy (“HSLA”) steel, which is a lighter, stronger steel used in automotive, structural, and pipeline applications. Scandium can be combined with Aluminum to make an alloy with increased strength and improved corrosion resistance. Scandium is also a critical component of advanced solid oxide fuel cells. Titanium is a key component of pigments used in paper, paint and plastics and is also used for aerospace applications, armor and medical implants.

For further information, contact John Ashburn, Vice President and General Counsel at (720) 639-4650 or at [email protected]

Special note about forward-looking statements:

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.

Certain statements contained in this press release may constitute forward-looking statements. Such forward-looking statements are based upon NioCorp’s reasonable expectations and business plan at the date hereof, which are subject to change depending on economic, political and competitive circumstances and contingencies. Readers are cautioned that such forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause a change in such assumptions and the actual outcomes and estimates to be materially different from those estimated or anticipated future results, achievements or position expressed or implied by those forward-looking statements. Risks, uncertainties and other factors that could cause NioCorp’s plans or prospects to change include changes in demand for and price of commodities (such as fuel and electricity) and currencies; changes or disruptions in the securities markets; legislative, political or economic developments; the need to obtain permits and comply with laws and regulations and other regulatory requirements; the possibility that actual results of work may differ from projections/expectations or may not realize the perceived potential of NioCorp’s projects; risks of accidents, equipment breakdowns and labor disputes or other unanticipated difficulties or interruptions; the possibility of cost overruns or unanticipated expenses in development programs; operating or technical difficulties in connection with exploration, mining or development activities; the speculative nature of mineral exploration and development, including the risks of diminishing quantities of grades of reserves and resources; and the risks involved in the exploration, development and mining business. NioCorp disclaims any intention or obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise.