Experiments on propagation and compression of pulses in an acoustic waveguide are described. A water filled channel of 32 ft length with pressure release surfaces is used as an acoustic waveguide with a cutoff frequencyfc=13.5 kc. Measurements on transient waveforms and on the dispersion curve of the guide in the frequency range between 13.5 and 26 kc are reported. In the pulse compression experiments the wave‐guide is used as a “matched filter” with a frequency‐dependent delay time. A frequency modulated input pulse of 12.6 msec length is compressed into an output pulse of shorter duration and of higher peak amplitude. The frequencies in the input pulse vary from 14 to 22 kc. A time compression ratio of 52.5:1 and a peak amplitude gain of 18.6 db are achieved experimentally. The detection of a pulse in the presence of noise for an input signal to noise ratio of −20 db is illustrated.