Piezoceramic transducers with matching layers are usually used to generate an ultrasonic wave in the air within the frequency range above 100 kHz. The paper presents a new material composition of low acoustic impedance named ITAKOM, whose acoustic characteristics makes it applicable as a matching medium between a piezoelectric transducer and a gas medium in a wide range of frequencies. Porosity is the common feature of all the lowest acoustic impedance materials. The results of the studies of different material compositions show that pore diameters and their percentage in the composite volume have greater importance than the composite make-up and render possible the elaboration of a composite material whose parameters can be defined by the percentage interdependence of components. Due to the comparatively wide range of density and wave velocity materials of acoustic impedance ranging from 0.2 −1×106 Pa⋅s/m can be produced. An example of an application of this material to construct the focusing ultrasonic transducer operating in the air at the frequency f=1.3 MHz in the setup of phase sensitive scanning acoustic microscopy as well as the results of object measurements are presented in the ultrasonic journal [Gudra et al., Ultrasonics 34, 711–719 (1996)].