Addex Raises $10.0 Million in Equity Financing Ad Hoc Announcement Pursuant to Art. 53 LR Geneva, Switzerland

Addex Raises $10.0 Million in Equity Financing

Ad Hoc Announcement Pursuant to Art. 53 LR

Geneva, Switzerland, December 17, 2021

- Addex Therapeutics Ltd (SIX: ADXN and Nasdaq: ADXN), a clinical-stage pharmaceutical company pioneering allosteric modulation-based

drug discovery and development, today announced that it has entered into a definitive agreement with Armistice Capital LLC, a healthcare-focused

institutional investor, pursuant to which the Company agreed to sell 3,752,202 shares in the form of 625,367 American Depositary Shares

("ADSs") at a gross purchase price of $6.50 per ADS, which is equivalent to CHF 1.00 per share. Each ADS represents

six shares. Additionally, Addex has agreed to issue to Armistice Capital unregistered warrants to purchase up to 9,230,772 shares in the

form of 1,538,462 ADSs (the "Unregistered Warrants"), as well as unregistered pre-funded warrants to purchase up to 5,478,570

shares in the form of 913,095 ADSs (the "Unregistered Pre-Funded Warrants" and together with the Unregistered Warrants, the

"Warrants") in a concurrent private placement. The Unregistered Warrants have an exercise price of $6.50 per ADS, will

become exercisable in 60 days after their date of issuance and will expire six years from their date of issuance. The Unregistered Pre-Funded

Warrants have been funded to the amount of $6.49 with $0.01 payable on exercise.

The gross proceeds to Addex, before deducting

placement agent fees and other offering expenses, will be $10.0 million. Addex intends to use the net proceeds from this offering to advance

its clinical and preclinical pipeline.

The closing of the offering is expected to occur

on or about December 21, 2021, subject to the satisfaction of customary closing conditions.

H.C. Wainwright & Co. is acting as the

exclusive placement agent for the offering.

The shares (but not the

Warrants or the shares underlying the Warrants) are being offered by Addex pursuant to a "shelf" registration statement

on Form F-3 that was originally filed on April 7, 2021 and declared effective by the Securities and Exchange Commission

("SEC") on April 13, 2021 and the base prospectus contained therein (File No. 333-255089). The offering

of the shares is being made only by means of a prospectus supplement that forms a part of the registration statement. Electronic copies

of the prospectus supplement and accompanying base prospectus may be obtained, when available, on the SEC's website at http://www.sec.gov

or by contacting H.C. Wainwright & Co., LLC at 430 Park Avenue, 3rd Floor, New York, NY 10022, by phone at 646-975-6996

or e-mail at placements@hcwco.com.

The Warrants and shares

underlying the Warrants are being offered in a private placement under Section 4(a)(2) of the Securities Act of 1933, as amended

(the "Act"), and Regulation D promulgated thereunder and, along with the shares underlying the Warrants, have not been registered

under the Act, or applicable state securities laws. Accordingly, the Warrants and underlying shares may not be offered or sold in the

United States except pursuant to an effective registration statement or an applicable exemption from the registration requirements

of the Act and such applicable state securities laws.

This press release shall not constitute an offer

to sell or a solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or other jurisdiction

in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any

such state or other jurisdiction.

About Addex Therapeutics:

Addex Therapeutics is a clinical-stage pharmaceutical

company focused on the development and commercialization of an emerging class of novel orally available small molecule drugs known as

allosteric modulators for neurological disorders. Allosteric modulators offer several potential advantages over conventional non-allosteric

molecules and may offer an improved therapeutic approach to conventional "orthosteric" small molecule or biological drugs.

Addex's allosteric modulator drug discovery platform targets receptors and other proteins that are recognized as essential for therapeutic

intervention. Addex's lead drug candidate, dipraglurant (mGlu5 negative allosteric modulator or NAM), is in a pivotal registration clinical

trial for Parkinson's disease levodopa induced dyskinesia (PD-LID) and has entered a Phase 2 clinical study for the treatment of

blepharospasm, a form of dystonia. Addex's third clinical program, ADX71149 (mGlu2 positive allosteric modulator or PAM), developed in

collaboration with Janssen Pharmaceuticals, Inc., is in a Phase 2a proof of concept clinical trial for the treatment of epilepsy.

Indivior PLC has licensed Addex's GABAB PAM program for the development of drug candidates with a focus in substance use disorder.

Preclinical programs include GABAB PAM for CMT1A, mGlu7 NAM for PTSD, mGlu2 NAM for mild neurocognitive disorders, mGlu4 PAM for

Parkinson's disease and mGlu3 PAM for neurodegenerative disorders. Addex shares are listed on the SIX Swiss Exchange and American

Depositary Shares representing its shares are listed on the NASDAQ Capital Market, and trade under the ticker symbol "ADXN"

Forward Looking Statements:

This press release contains forward-looking statements

within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including in respect of the anticipated closing

of the offering described above. The words "may," "will," "could," "would," "should,"

"expect," "plan," "anticipate," "intend," "believe," "estimate,"

"predict," "project," "potential," "continue," "target" and similar expressions

are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any

forward-looking statements in this press release, such as the expected closing date and use of proceeds from the offering, are based on

management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause

actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press

release, including, without limitation, uncertainties related to market conditions and the satisfaction of customary closing conditions

related to the offering. These and other risks and uncertainties are described in greater detail in the section entitled "Risk Factors"

in Addex Therapeutics' Annual Report on Form 20-F for the year ended December 31, 2020, as filed with the SEC on March 11,

2021, the final prospectus supplement and accompanying prospectus and other filings that Addex Therapeutics may make with the SEC in the

future. Any forward-looking statements contained in this press release represent Addex Therapeutics' views only as of the date hereof

and should not be relied upon as representing its views as of any subsequent date. Addex Therapeutics explicitly disclaims any obligation

to update any forward-looking statements.