Experiments are described in which quanta emitted by water under alpha-particle bombardment have been detected. Differentiation between light pulses arising from liquid water and any gas present above the water surface has been accomplished by utilizing the difference in their times of duration. From measurements made of the absorption of the quanta from water by various gases an upper limit of the wavelength of 1900 Å is suggested. The importance of quantum emission in radiation chemical experiments is discussed but, owing to the apparently very high absorption coefficient of the water, it is difficult to assess the contribution from this phenomenon.