SYRACUSE, N.Y.--(BUSINESS WIRE)--July 22, 2010-- Niagara Mohawk Power Corp., a subsidiary of National Grid plc (NYSE: NGG), announced that its Board of Directors has declared dividends at the following rates for all series of its preferred stock. .85% of $100 par value on the 3.40% Series; .90% of $100 par value on the 3.60% Series; .975% of $100 par value on the 3.90% Series. Preferred stock dividends are payable September 30, 2010, to holders of record September 8, 2010. Niagara Mohawk Power Corp., doing business as National Grid, provides electricity service to approximately 1.5 million customers and natural gas service to approximately 565,000 customers in upstate New York. The company is based in Syracuse, N.Y. Its parent company also has electricity and gas distribution operations in New England. CONTACT: For National Grid Courtney Quatrino, 315-428-5891 Note: This contact is for media inquiries only. SOURCE: National Grid plc Copyright Business Wire 2010 Order free Annual Report for National Grid PLC Visit http://djnweurope.ar.wilink.com/?ticker=GB00B08SNH34 or call +44 (0)208 391 6028 (END) Dow Jones Newswires July 22, 2010 07:55 ET (11:55 GMT)