NEWS

Vancouver, British Columbia – September 22, 2014 – NioCorp Developments Ltd. (“NioCorp” or the “Company”) (TSX-V: NB, OTCQX: NIOBF, FSE: BR3) is pleased to announce an updated NI43-101 resource estimate for the Elk Creek niobium deposit.

Commencing in May, the Company initiated a three phase technical infill drilling program, with multiple goals of enhancing the classification of the resource; producing geotechnical and geochemical analysis of the deposit; provide material for the use in metallurgical studies including pilot plant; and to provide all other necessary information required to create and design a mine plan.  Additional drilling to enhance the overall size of the deposit, where it remains open to the northwest, southeast, and at depth, will be carried out in the future.

The Company has completed the phase 1, five-hole drill program for a total of 5,011 m, with the phase 2, six-hole drill program now currently underway.  Phase 3 will follow, if necessary.  Utilizing historic and phase 1 drilling results, SRK Consulting (“SRK”) of Lakewood, Colorado and Cardiff, UK have completed an updated mineral resource estimate.

SRK’s Mineral Resource is based on a robust 3D model of grade trends within the carbonatite complex and is based on good QAQC results. Higher grades are associated with pyrochlore contained in magnetite bearing dolomitic carbonatite. The Indicated Mineral Resource is confined to a single coherent well drilled area containing continuous high grade features.

The estimate has been reported according to CIM Standards and will be supported by a NI43-101 independent report which will be published in due course.

The resource estimate for the Elk Creek deposit is summarized in Table 1 below:

Table 1 – SRK Mineral   Resource Statement Effective Date 9th September 2014

Classification

Cut-off (Nb2O5   %)

Tonnage

(‘000 Tonnes)

Grade (Nb2O5   %)

Contained Nb2O5

(‘000 kg)

INDICATED

0.30

28,200

0.63

177,000

INFERRED

0.30

132,800

0.55

733,700

(1) Mineral Resources are not Mineral Reserves   and do not have demonstrated economic viability. All figures are rounded to   reflect the relative accuracy of the estimate and have been used to derive   sub-totals, totals and weighted averages.   Such calculations inherently involve a degree of rounding and consequently   introduce a margin of error. Where these occur, SRK does not consider them to   be material. All composites have been capped where appropriate. The   Concession is wholly owned by and exploration is operated by Niocorp   Developments Ltd

(2) The reporting standard adopted for the   reporting of the MRE uses the terminology, definitions and guidelines given   in the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Standards   on Mineral Resources and Mineral Reserves (December 2005) as required by NI   43-101.

(3) SRK assumes the Elk Creek deposit to be   amenable to a variety of Underground Mining methods. In the absence of definitive pricing for Nb   and established rates of metallurgical recovery, SRK has reported the Mineral   Resource at a cut-off of 0.3% Nb2O5. The Company’s previous Mineral Resource   dated April 2012 was calculated at a cut-off of 0.4% Nb2O5.

(4) SRK Completed a site inspection to the   deposit by Mr Martin Pittuck, MSc., C.Eng, MIMMM , an appropriate   “independent qualified person” as this term is defined in National Instrument   43-101.

Given the current early stage in the other technical disciplines and on-going metallurgical testwork the sensitivity in the Mineral Resource at a range of preliminary cut-off grades is presented in Table 2 from 0.3% Nb2O5 to 0.5% Nb2O5.

Table 2 – SRK Mineral   Resource Sensitivity

Classification

Cut-off (Nb2O5   %)

Tonnage

(‘000 Tonnes)

Grade (Nb2O5   %)

Contained Nb2O5

(‘000 kg)

INDICATED

0.50

19,100

0.74

142,000

INDICATED

0.40

22,600

0.70

157,600

INDICATED

0.30

28,200

0.63

177,000

INFERRED

0.50

63,700

0.74

469,600

INFERRED

0.40

87,000

0.66

573,300

INFERRED

0.30

132,800

0.55

733,700

 Readers should note that this update only includes the results of phase 1 drilling operations. Work is currently on-going to improve the confidence in the current geological model through additional drilling and further validation of historical databases. Validation work is aimed to be completed with the completion of phase 2 drilling operations in the 4th quarter, at which point the company intends to deliver a follow up resource estimate which will include that data.

“Drill results have far exceeded our expectations on this deposit, and we are a very pleased to be able to deliver this resource update to shareholders,” stated Mark A. Smith, CEO of NioCorp.  “We are also very impressed with the significant progress being achieved on the metallurgy program as we rapidly approach the pilot plant test stage.  The information we now know, combined with the upcoming pilot plant results and the updated resource estimate before year end, will dovetail into the extensive engineering design work that SRK are diligently completing, in order to fully meet our overall objectives for this world-class project.”

The Company will file the complete NI43-101 compliant report on SEDAR and it will be available on the Company’s website within the prescribed timeline.

Qualified Persons: Martin Pittuck, MSc., C.Eng, MIMMM of SRK Consulting (UK) Ltd., a Qualified Person as defined by National Instrument 43-101, is responsible for the Elk Creek resource estimation and has read and approved the technical information contained in this news release.

About the Company:  NioCorp are 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 an NI43-101 compliant resource report, available on SEDAR, and is in the process of filing the updated NI43-101 compliant resource estimate reported in this press release.  Niobium is mainly used in the form of Ferro-Niobium to produce HSLA (High Strength, Low Alloy) steel, to produce lighter, stronger steel for use in automotive, structural and pipeline industries.  The U.S. imports 100% of its niobium needs.

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

ON BEHALF OF THE BOARD

“Peter Dickie”        Director, President and Corporate Secretary

Neither 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.