This paper describes an innovative method for measuring the mean and the local film thickness within the mixing duct of a Y-jet atomizer. The method is based on impedance measurements between two suitably shaped electrodes, immersed in a dielectric test atomizer. The data obtained by means of this technique have been compared with the results of an experimental characterisation of the spray structure by Phase Doppler Particle Analyser. A simple model allowed to evaluate the film flowrate from the measured value of film thickness. Information on liquid film characteristics is of paramount importance in determining optimal operating conditions and design criteria for Y-jet atomizers.