A Differential Mobility Particle Sizer (DMPS) system has been adapted and tested for reliable aerosol characterization at stratospheric pressures and temperatures in the AIDA aerosol chamber of Forschungszentrum Karlsruhe. To avoid partial or complete evaporation of volatile aerosol particles (e.g. solution droplets like sulfuric acid droplets), the DMA is operated at almost the same temperature and pressure as the AIDA aerosol vessel. In this study, we describe the experimental setup and technical modifications to the TSI standard DMA 3071 and CPC 3010 used for the DMPS system, discuss the results of low pressure Latex calibration and CPC counting efficiency measurements, and demonstrate the performance of the entire system in a case study with sulfuric acid aerosol. (C) 2004 Elsevier Ltd. All rights reserved.