A NASA U-2 research aircraft flew sampling mission in April, May, July, November, and December 1982 aimed at obtaining in situ data in the stratospheric cloud produced from the March-April 1982 El Chichon eruptions. Aerosol particles were samples using a quartz crystal microbalance (QCM) cascade impactor. Post flight analyses with scanning electron microsopy (SEM), energy dispersive X-ray analysis (EDXRA), and Auger spectroscopy provided information on the aerosol composition and morphology. The particles ranged in size from smaller than 0.05m to larger than 20 m diameter and were quite complex in composition. In the April, May, and July samples the aerosol mass were dominated by magmatic and lithic particles larger than about 3 m. The submicrop particles consisted largely of sulfuric acid. Halite particles, believed to be related to a salt dome beneath El Chichon, were collected in the stratosphere in April and May. On the July 23 flight, copper-zinc oxide particles were collected. In July, November, and December, in addition to the volcanic ash and acid particles, carbon-rich particles smaller than about 0.1 m aerodynamic diameter were abundant.