The Duchess of Cambridge will carry out her first engagement as Honorary Air Commandant of the Air Cadets by marking their 75th anniversary.
Kate assumed the role in December, taking on the post from the Duke of Edinburgh who had been involved with the organisation for more than 60 years.
The Duchess now represents 42,000 air cadets aged from 12 to 19, and 15,000 adult volunteers at more than 1,200 units across the UK and abroad.
At the RAF church of St Clement Danes in central London on Sunday Kate will join the congregation for a service to mark the anniversary.
Afterwards she will be guest of honour at a reception at the Royal Courts of Justice where the cadets will get the chance to meet their new patron.
The Duchess will also have the chance to learn more about their numerous programmes and activities by chatting to cadets, veterans and adult volunteers
The RAF Air Cadets comprises both the Air Training Corps (ATC) and the Combined Cadet Force (RAF).
The ATC was first established in 1941 during the Second World War, with the aim of training young men in aviation skills before they joined the RAF.