Exhibit 99.1

FOR IMMEDIATE RELEASE

September 23, 2010

Vical Incorporated Announces Proposed Public Offering of Common Stock

SAN DIEGO—September 23, 2010—Vical Incorporated (NASDAQ:VICL) today announced that it is offering to sell shares of its common stock in an underwritten public offering. Jefferies & Company, Inc. is acting as sole book-running manager in the offering, Stifel Nicolaus Weisel is acting as co-lead manager for the offering and Canaccord Genuity Inc. is acting as co-manager for the offering. The offering is subject to market conditions, and there can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering.

The securities described above are being offered by Vical pursuant to a shelf registration statement previously filed with and declared effective by the Securities and Exchange Commission (the “SEC”) on January 29, 2010. A preliminary prospectus supplement related to the offering will be filed with the SEC and will be available on the SEC’s Web site at http://www.sec.gov. Copies of the preliminary prospectus supplement relating to these securities may be obtained from Equity Syndicate Prospectus Department, Jefferies & Company, 520 Madison Avenue, 12th Floor, New York, NY, 10022, at 877-547-6340, and at Prospectus_Department@Jefferies.com. This press release shall not constitute an offer to sell or the 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 Vical Incorporated

Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases.

-more-

Vical/page 2

In addition to historical facts, this press release contains forward-looking statements that involve a number of risks and uncertainties such as those, among others, relating to Vical’s expectations regarding the completion, timing and size of its proposed public offering. Among the factors that could cause actual results to differ materially from those indicated in the forward-looking statements are risks and uncertainties associated with market conditions and the satisfaction of customary closing conditions related to the proposed offering, as well as risks and uncertainties associated with Vical’s business and finances in general, and the other risks described in Vical’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2010, and in the preliminary prospectus supplement related to the proposed offering to be filed with the Securities and Exchange Commission. Vical undertakes no obligation to update the statements contained in this press release after the date hereof.

#          #          #