A Fast Integrated Mobility Spectrometer (FIMS) has been developed for sub-second aerosol size distribution measurements based on the description presented in the preceding paper (Paper 1). The performance of FIMS was characterized using DMA classified aerosols in the size range 15-170 nm. An excellent agreement was observed between the mean particle diameter measured by FIMS and the DMA centroid diameter. Comparison of particle concentrations measured by FIMS and a Condensation Particle Counter (CPC) shows that counting efficiency of FIMS is 100% for particles larger than 20 nm, and higher than that of the CPC for particles with diameters less than 15 nm. Experimentally determined FIMS mobility resolution ranged from 5 to 14 for particle diameters between 22 to 170 nm, and agreed with theoretical predictions made using FIMS transfer theory, though there was some deviation observed at particle sizes that correspond to high theoretical mobility resolution. (c) 2006 Elsevier Ltd. All rights reserved.