Holding(s) in Company

Proton Power Systems PLC
02 November 2007



                            Proton Power Systems plc
                       ('Proton Power' or the 'Company')


                               Holding in Company

Proton Power was notified on 1 November 2007 that The Royal Bank of Scotland
Group plc had a notifiable interest of 2,500,000 ordinary shares of 5 pence each
in the Company, representing 7.96% of the issued ordinary share capital of the
Company.  This interest arises from the acquisition of ABN AMRO Holding N.V. by
RFS Holdings N.V., of which The Royal Bank of Scotland Group plc is the ultimate
parent.

The issued share capital of the Company is 31,390,863 ordinary shares of 5 pence
per share.

                                    - Ends -

For further information:

Proton Power Systems plc
Felix Heidelberg, CEO                                  Tel: [phone]
[e-mail]                          www.protonpowersystems.com




Noble & Company Limited   
Graeme Bayley / Andy Yeo                               Tel: [phone]
                                                                 www.noblegp.com


Media enquiries:

Abchurch Communications Limited
Justin Heath / Franziska Boehnke                       Tel: [phone]
[e-mail]                      www.abchurch-group.com



Notes to Editors

Proton Power Systems plc is a developer of fuel cells and fuel cell hybrid
systems for motive and back-up power supply. Proton Power has more than 13 years
of experience in the fuel cell market. Through its wholly owned subsidiary,
Proton Motor Fuel Cell GmbH, the Company has developed and produced a fuel cell
module running on hydrogen and integrated this with an energy storage system to
create a hybrid electric fuel cell system. The system harnesses the excess power
generated by the fuel cell during partial load (such as stop-start operations)
and uses the stored energy in peak demand times. The system thus boasts lower
fuel consumption and more consistent levels of power delivery than conventional
combustion engine or fuel cell-only systems, in addition to producing zero
harmful emissions.

Proton Power's market focus lies in industrial applications where 'back-to-base'
refuelling occurs at the end of each shift or work period, such as in the
materials handling and mass transportation sectors. In these markets, the
commercialisation of applications is possible at a very early stage, as they do
not depend on the existence of a ubiquitous hydrogen infrastructure. Through
partnerships with leading OEMs such as Skoda Electric and Linde, Proton Power's
technology is already deployed in city buses and forklift trucks.

Proton Power also targets the upcoming market for marine transportation
applications and provides the hybrid fuel cell propulsion system for Europe's
first fuel-cell powered passenger / river boat ferry, which will be operating in
Hamburg from 2008.

Proton Power Systems plc was admitted to trading on AIM on 31 October 2006 and
is based in the UK. Its operating subsidiary, Proton Motor Fuel Cell GmbH, is
located in Puchheim, near Munich, Germany.



                      This information is provided by RNS
            The company news service from the London Stock Exchange   D

HOLUUOWRBVRARRA