The work was concerned with the simultaneous measurement of the combination coefficients b and eta ₀, between small ions and aerosol particles, and between small ions and uncharged aerosol particle respectively, for different particle radii. The ion-ion mutual repulsion coefficient gamma had a mean experimental value of 2.39 (+or-0.14)*10^-6 cm³ s^-1. The decay of ions in the presence of aerosol particles in a mylar vessel was recorded and compared with a family of computed theoretical ion-aerosol decay curves to determine b. eta ₀ could then be determined from concentration of uncharged nuclei present. Satisfactory agreement was found between the b eta ₀ versus radius results and various theoretically computed values. Possible reasons for discrepancies between theory and experiment are indicated.