The comparative studies of water absorption rate (V) and the intensity (I) of ultraweak luminescence (UWL) emitted by samples of wheat grain during the first 15 min of swelling were carried out. The V rate was estimated using the capillary method in which the volume changes of water in the capillary vessel within each 1 min period were measured. The intensity I was measured using high sensitivity apparatus working in the single-photon-counting arrangement As a result of the experiment several kinetic curves of V rate and the intensity I, as well as the dependencies between V and I obtained in the initial periods of grain imbibition, have been presented. It was found that the V rate and the intensity I depend on the thickness, mechanical damage, initial moisture content and temperature of grain. Comparing the results, it has been found explicitly that the intensity I depends on the water absorption rate V by wheat grain.