Additional Listing & Director Shareholding

31 March 2011

Hydro International plc

("Hydro", the "Company" or the "Group")

Additional Listing, Director's Holding and Total Voting Rights

Additional Listing

The Company announces that pursuant to the terms of its Incentive Stock Option Plan, options over 47,500 ordinary shares of 5p each have been exercised.

Application has been made for admission of these shares to trading on AIM. The new ordinary shares will rank pari passu in all respects with the Company's existing ordinary shares. It is expected that Admission of the new ordinary shares will become effective on or around 6 April 2011.

Director's Holding

The Company announces that it has today been notified that, pursuant to the terms of its Incentive Stock Option Plan, options over 47,500 ordinary shares of 5p each have been exercised by Mr Robert Y G Andoh, at a price of 33.0 pence each. Mr Andoh is a Director of the Company.

Following the exercise of these options Mr Andoh holds a total of 163,062 shares in the Company, representing 1.14% of the issued share capital.

Total Voting Rights

For the purposes of the Financial Services Authority's Disclosure and Transparency Rules, the total number of ordinary shares of 5p of Hydro International plc in issue as at the date of this notice is 14,361,787 with each share carrying the right to one vote.

There are no shares held in treasury.

The total number of voting rights in Hydro International plc is therefore 14,361,787.

The above figure may be used by shareholders as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, Hydro International plc, under the Disclosure and Transparency Rules.

For further information please contact:

About Hydro International

Hydro International plc (AIM:HYD.L) (Hydro) is a global supplier of environmentally sustainable products and innovative solutions for the control and treatment of stormwater, wastewater and combined sewer overflows. Hydro's products use a range of advanced technologies including award-winning advanced vortex technology. Headquartered in Clevedon, North Somerset, Hydro also operates in the UK from offices in Ely, Cambridgeshire as well as across the US from bases in Portland, Maine and Hillsboro, Oregon. The Group has a growing presence outside of its core US and UK markets in Ireland, Egypt, Middle East, European Union, Malaysia, Singapore, Japan, Korea, Australia and New Zealand.

Please visit the website for further information www.hydro-international.biz.