Toronto, November 03, 2020 – O3 Mining Inc. (TSX.V:OIII) (“O3 Mining” or the “Corporation”) is pleased to provide new drilling results from the Malartic Property in Val D’Or, Quebec, as part of its fully-funded 150,000 metre drilling program.

Current drilling on the Malartic property is focused on expanding mineralization outside of the proposed pit areas outlined in the Preliminary Economic Assessment (PEA) released on September 8^th, 2020. The 2020-2021 drilling program considers 45,000 metres on the Malartic property to test extensions of the deposits and zones outside of the PEA pit areas. New analytical results from four drill holes cutting the Kierens deposit extensions at 25 meters below surface include:

Drilling Highlights:

• 2.9 g/t Au over 14.2 metres in hole O3MA-20-006, including 18.5 g/t Au over 1.0 metre

• 2.1 g/t Au over 10.5 metres in hole O3MA-20-005

These drill holes have been drilled from the same collar located between the Kierens and Norlartic deposits, 145 meters SE of the Kierens pit shell limit and 325 meters from the NW limit of the Norlartic pit shell. The primary objective of these holes was to cross the Kierens-Norlartic corridor at shallow depth while drilling the extensions at depth of the Gold Hawk zone. These new results suggest that the Kierens ore body comes closer to the surface than previously interpreted and, when properly delineated, could favorably impact a future update of the in-pit resource.

We are pleased with these latest drill results as they show that drilling can continue to expand the mineral footprint at the various deposits on our Malartic property, which bodes well for growing the resource base and making the Marban Alliance project development even more attractive. We also received the pleasant surprise of intercepting mineralization just below the surface, which could have a meaningful positive impact in a future production scenario.”President and CEO José Vizquerra

Table 1: Drill Hole Intercepts (only intercepts above 5 g/t Au * m are reported, cut-off 0.3 g/t Au)

Note

True width determination is currently unknown but is estimated at 65-80% of the reported core length interval for the zones.

Table 2: Drill Hole Details

The high-grade gold veins at Gold Hawk have been outlined by many different drilling programs since the 1980s. Drilling at 30-metre spacing and to a vertical depth of 400 metres identified three veins or vein systems named Vein #1, #2, and #3, remains open at depth. Non 43-101 compliant resource suggests 254,000t grading 8.6g/t Au at Gold Hawk (Sigeom).

Drill holes O3MA-20-003 to O3MA-20-006 all intersected the Kierens-Norlartic mineralized zone at shallow depth at approximately 6 metres apart. The mineralized zone is associated with up to 5% disseminated pyrite within a brecciated gabbroic dyke with 15% quartz-carbonate-chlorite veining. The dyke is located at the contact with a sheared ultramafic unit and corresponds to the geological context described by previous operators of the Kierens horizon.

Figure 1: Malartic Property Map

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Figure 2: Marban Alliance Project Drilling Map

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Qualified Person

The scientific and technical content of this news release has been reviewed, prepared, and approved by Mr. Louis Gariepy. (OIQ #107538), VP Exploration, who is a “qualified person” as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).

Quality Control and Reporting Protocols

True width determination is currently unknown but is estimated at 65-80% of the reported core length interval for the zones. Assays are uncut except where indicated. Intercepts occur within geological confines of major zones but have not been correlated to individual vein domains at this time. Half-core samples are shipped to Agat laboratory in Val D’Or, Quebec and Mississauga, Ontario for assaying. The core is crushed to 75% passing -2 mm (10 mesh), a 250 g split of this material is pulverized to 85% passing 75 microns (200 mesh) and 50 g is analyzed by Fire Assay (FA) with an Atomic Absorption Spectrometry (AAS) finish. Samples assaying >10.0 g/t Au are re-analyzed with a gravimetric finish using a 50 g charge. Commercial certified standard material and blanks are systematically inserted by O3 Mining’s geologists into the sample chain after every 18 core samples as part of the QA/QC program. Third-party assays are submitted to other designated laboratories for 5% of all samples. Drill program design, Quality Assurance/Quality Control (“QA/QC”) and interpretation of results are performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices.

About O3 Mining Inc.

O3 Mining, which forms part of the Osisko Group of companies, is a mine development and emerging consolidator of exploration properties in prospective gold camps in Canada – focused on projects in Québec and Ontario – with a goal of becoming a multi-million ounce, high-growth company.

O3 Mining is well-capitalized and holds a 100% interest in properties in Québec (435,000 hectares) and Ontario (25,000 hectares). O3 Mining controls 61,000 hectares in Val D’Or and over 50 kilometres of strike length of the Cadillac-Larder Lake Faut. O3 Mining also has a portfolio of assets in the James Bay and Chibougamau regions of Québec.

Cautionary Note Regarding Forward-Looking Information

This news release contains “forward-looking information” within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections, and interpretations as at the date of this news release. The information in this news release about the transaction; and any other information herein that is not a historical fact may be “forward-looking

information”. Any statement that involves discussions with respect to predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often but not always using phrases such as “expects”, or “does not expect”, “is expected”, “interpreted”, “management’s view”, “anticipates” or “does not anticipate”, “plans”, “budget”, “scheduled”, “forecasts”, “estimates”, “believes” or “intends” or variations of such words and phrases or stating that certain actions, events or results “may” or “could”, “would”, “might” or “will” be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward-looking information. This forward-looking information is based on reasonable assumptions and estimates of management of the Corporation, at the time it was made, involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the companies to be materially different from any future results, performance or achievements expressed or implied by such forward-looking information. Such factors include, among others, risks relating to the restart of operations; further steps that might be taken to mitigate the spread of COVID-19; the impact of COVID-19 related disruptions in relation to the Corporation’s business operations including upon its employees, suppliers, facilities and other stakeholders; uncertainties and risk that have arisen and may arise in relation to travel, and other financial market and social impacts from COVID-19 and responses to COVID 19. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions, the parties cannot assure shareholders and prospective purchasers of securities that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither the Corporation nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information. The Corporation does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.

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 news release. No stock exchange, securities commission or other regulatory authority has approved or disapproved the information contained herein.

For further information on O3 Mining, please contact:

José Vizquerra Benavides

President, CEO and Director

Telephone: (416) 363-8653

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