The papers contain biographical material (including three chapters of an uncompleted autobiography), speeches and publications. There are 105 manuscript notebooks which fall into three separate groups: Cambridge notes by Powell on lectures by Rutherford, C.T.R. Wilson and others; Bristol notebooks, 1939-1949, of cosmic ray observations by Powell and his team; and notebooks of miscellaneous material such as drafts by Powell for his own lectures, speeches or publications, notes taken at conferences, etc. There are also journals, notebooks and reports relating to the Royal Society expedition to Montserrat in 1936 to investigate earth tremors on which Powell served as seismologist. Except for a few letters dealing with publications, there is no personal or professional correspondence. Documents (including correspondence) dealing with Powell's work for international organisations were destroyed after his death.
The supplementary papers include biographical material such as congratulatory letters on the Nobel Prize, Powell's sixtieth birthday and the Lomonosov Gold Medal, and family letters. Powell's research is represented chiefly by contemporary letters recording the high altitude balloon flights in Sardinia in 1952 and 1953. There are also photographs relating to Powell's scientific work and some drafts for lectures, addresses and broadcasts. Powell's public life in national and international affairs remains scantily documented, only a few records of Pugwash conferences and a little correspondence, disproportionately skewed towards the second half of the alphabet, surviving what was believed to be the wholesale destruction of his correspondence and papers after his death.