The detection and characterization of breaking waves using X-band pulsed Doppler microwave radar are studied experimentally. Field experiments were conducted at the Shuang-Si estuary in the north of Taiwan in the winter of 2005. Results show that the maxima radar cross section and Doppler frequency shift can be used to characterize wave breaking zones. Base on observations of breaking waves, the wave breaking zones are shown to be located at water depths of 1.8 to 2.2 m in the experimental site. In general, the results indicate that a radar system has the potential to delineate the spatial variation of breaking waves clearly and that this is sufficient to achieve a measurement operation for near-shore air-sea interaction events.