The Prince of Wales will attend a Battle of Britain commemoration service at Westminster Abbey, before hosting a reception for veterans and their families.
The annual service of thanksgiving and rededication will this year mark the 75th anniversary of the remarkable victory, and the loss of life by Royal Air Force pilots and aircrew.
Scotland's First Minister Nicola Sturgeon and Defence Secretary Michael Fallon will also attend today's service.
Charles will later meet veterans at a nearby reception before watching a flypast of four spitfire and two hurricanes.
The service comes after the biggest gathering of Battle of Britain aircraft since the Second World War to mark the aerial conflict's 75th anniversary on Tuesday, attended by Prince Harry.
The 1940 Battle of Britain was the first major campaign to be fought entirely in the skies, with the help of servicemen from Australia, Belgium, Canada, Czechoslovakia France, Ireland, Jamaica, New Zealand, Poland, Rhodesia, South Africa, America and Newfoundland.
Over 544 RAF pilots and aircrew died in the critical phase of the Second World War.
Charles has attended the Battle of Britain service over 10 times, including the 50th, 60th and 70th anniversaries.
In 2010, he commissioned 15 portraits of surviving servicemen by alumni and faculty of The Prince's Drawing School, one of The Prince's Charities.
They were displayed for the veterans and their families at Church House during the reception after the service in 2012.