CENTENNIAL, Colo. – September 15, 2015 – NioCorp Developments Ltd. (“NioCorp” or the “Company”) (TSX: NB; OTCQX: NIOBF; and FSE: BR3) announces that it will conduct a non-brokered private placement of unsecured convertible promissory notes (the “Notes”), for gross proceeds of up to USD$750,000 (the “Private Placement”).

The Notes will bear interest at a rate of 8%, payable annually in arrears, are non-transferable and have a term of three years from the date of issue. Principal under the Notes is convertible by lenders into, and payable by the Company in, common shares of the Company at a conversion price of CAD$0.97 per common share, calculated on conversion or repayment using the then-current Bank of Canada noon exchange rate. Accrued but unpaid interest on the Notes will be convertible by lender into, and payable by the Company in, common shares at a price per common share equal to the most recent closing price of the Company’s common shares prior to the delivery to the Company of a request to convert interest, or the annual due date of interest, as applicable, calculated using the then-current Bank of Canada noon exchange rate.

All securities issued under the Private Placement will be subject to a four month hold period, and the completion of the Private Placement is subject to Toronto Stock Exchange approval. The Company expects to use the proceeds of the Private Placement for general working capital purposes.

About the Company:

NioCorp is a mineral development company pursuing high-quality natural resources. The Company’s main focus is the Elk Creek Niobium Project, which is an advanced niobium exploration initiative located in southeast Nebraska. This resource is used to produce High Strength, Low Alloy (“HSLA”) steel, which is a lighter, stronger steel used in automotive, structural, and pipeline applications.

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

Cautionary 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.