The propagation of pressure waves in a liquid with gas bubbles has been adequately investigated over the last 30 years both theoretically and experimentally [1‐5]. In particular, a nonlinear finite-duration perturbation in a liquid with gas bubbles was shown to decompose into solitary waves (solitons), whose evolution and structure were studied in detail. The heat exchange between a gas in bubbles and an ambient liquid was shown to be the basic mechanism of wave dissipation in bubble media over a wide range of their parameters. In [6, 7], the structure and attenuation of solitary pressure waves with moderate amplitude were investigated experimentally in a liquid with gas bubbles uniform in size. Allowance for the polydispersity of a gas‐liquid medium leads to additional attenuation of pressure waves [8, 9]. New types of wave structures, multisolitons in a liquid with gas bubbles of two different sizes, were discovered in [10] for various ratios between the bubble radii. The effect of the inhomogeneity of a gas‐ liquid mixture and the compressibility of a liquid on the structure of a pressure wave was investigated in [11, 12]. The structure of upward and downward bubble flows was studied in [13, 14]. The gas phase is substantially redistributed over the pipe cross section even for low volume gas contents. Bubbles are almost entirely concentrated either in the central region of the pipe (downward flow) or in the near-wall region (upward flow). In this study, we experimentally investigated the evolution and attenuation of moderate-amplitude pressure waves in a liquid containing gas bubbles inhomogeneously (stepwise) distributed over a section transverse to the wave-propagation direction. The experiments were carried out in a shock tube. Its active region is a 1.5-m-long vertical thick-walled steel pipe with an inner diameter of 53 mm. A thinwalled (30- μ m-thick) Dacron pipe 37.5 mm in diameter was arranged inside the active region. The Dacron pipe was rigidly mounted by thin partitions to the active region. This region was filled with a liquid and saturated with gas bubbles by a generator arranged in the lower part of the pipe. The experiments were carried out for three structures of the bubble medium. Bubbles were supplied uniformly either over the cross section of the entire active region, over the ring between the Dacron pipe and the active-region wall (gas‐liquid ring), or inside the Dacron pipe (gas‐liquid column). The spread of gas-bubble sizes was equal to ∠ 5% . The mean bubble radius was equal to 0.53 mm. As a working liquid, we used the 50% (in mass) solution of glycerin in distilled water. Freon 12 and nitrogen having different thermal diffusivities were used as a gas phase. A volume gas‐bubble fraction average over both cross section and active-region length was determined from the liquid-level increase in the active region upon introducing gas bubbles and was equal to 0.5% for all of the experiments. The experiments were carried out at room temperature and atmosphere static pressure P 0 over the level of the gas‐liquid medium. Bell-shaped pressure waves were generated by an electromagnetic radiator arranged at the active-region bottom. A signal is formed when a thin copper plate is repulsed from the coil through which a current pulse flows. The pressure-wave profiles were detected by six piezoelectric pressure sensors arranged along the active region. The sensor signals were applied to an analog-todigital converter and processed by a computer. The experimental results showed that the inhomoge