Summary of ACTIVE POWER INC

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard;

Item 3.01 Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

On August 18, 2008, Active Power, Inc., a Delaware corporation (the "Company"), received a Staff Deficiency Letter from the NASDAQ Stock Market ("NASDAQ") notifying the Company that it fails to comply with NASDAQ's Marketplace Rule 4450(a)(5) (the "Rule") because the closing bid price for the Company's Common Stock, over the last 30 consecutive business days, has closed below the minimum $1.00 per share requirement for continued listing. The NASDAQ letter dated August 18, 2008 has no immediate effect on the listing of the Company's common stock.

In accordance with Marketplace Rule 4450(e)(2), the Company has a period of 180 calendar days, or until February 17, 2009, to regain compliance. If at any time before February 17, 2009, the bid price of the Company's Common Stock closes at or above $1.00 per share for a minimum of 10 consecutive business days, NASDAQ will provide written notification that the Company has achieved compliance with the Rule. If compliance with the Rule cannot be demonstrated by February 17, 2009, the Company's Common Stock will be subject to delisting from the NASDAQ Global Market.

In the event that the Company receives notice that its common stock is being delisted from The NASDAQ Global Market, NASDAQ rules permit the Company to appeal any delisting determination by the NASDAQ staff to a NASDAQ Listing Qualifications Panel. Alternatively, NASDAQ may permit the Company to transfer its common stock to The NASDAQ Capital Market if it satisfies the requirements for initial inclusion set forth in Marketplace Rule 4310(c), except for the bid price requirement. If its application for transfer is approved, the Company would have an additional 180 calendar days to comply with the Minimum Bid Price Rule in order to remain on The NASDAQ Capital Market.

The Company will continue to monitor the bid price for its common stock and consider various options available to it if its common stock does not trade at a level that is likely to regain compliance.

The Company issued a press release on August 19, 2008 that disclosed its receipt of this letter from NASDAQ. A copy of the press release is attached hereto as Exhibit 99.1.