<p>Condensation particle counters (CPCs) have been widely used for measuring aerosol particle number concentrations in the atmosphere. Here we present a laboratory evaluation of a portable type CPC (Model 3007, TSI) for mobile measurements of aerosol particles in ambient air, with specific focus on the measurements of aircraft exhaust ultrafine particles (UFPs). The laboratory experiments included the quantification of particle coincidence effects at higher concentrations, size-resolved detection efficiency of aerosol particles, and stability of detection efficiency without the supply of isopropyl alcohol (working fluid). We used a Faraday cup aerosol electrometer (in-house production) as a reference in the laboratory. We also present ambient measurement data obtained at Kobe Airport to assess the capability of the CPC 3007 to detect aircraft exhaust UFPs. An intercomparison with other CPCs shows the overall feasibility of using the CPC 3007 for ambient measurements of UFPs around airports and potential limitations of using it for measuring freshly emitted aircraft exhaust UFPs. </p> Graphical Abstract <p></p>