A relatively simple method was employed for measurement of water diffusivity in aqueous lithium bromide and lithium chloride solutions. The twin bulb apparatus used for these measurements was developed using an analogy between this apparatus and the conventional diaphragm cell apparatus. Tritiated water (TOH) was used as a tracer for these experiments because of its chemical similarity and proximity to the molecular weight of water. High tracer activity used at the beginning of the experiments allowed the use of relatively shorter time duration for each experiment (approximate to 20 h) and a quasi-steady state equation to calculate the diffusivity from the observed tracer activity data. Initially, the water diffusivity in lithium bromide solutions for concentrations varying from 0.5 M to 3 M (22.1 weight percent) was measured to obtain a comparison with published values. The lithium bromide concentration was further varied from 3 M to 11 M (57.4 weight percent) to obtain data in the concentration range usually employed in absorption cooling applications, which is near the solubility limit. The water diffusivity was found to vary with lithium bromide concentration, and to have a maximum of 16.7 x 10(-10) m(2)/s at 4 M. These diffusivity values were also compared with those obtained using an equation proposed by Rosevaere et al. (1941) for nonideal solutions. The water diffusivity in lithium chloride solutions was measured at concentrations of 7 M (25.7 weight percent) and 8M (28.87 weight percent) to obtain a comparison with published values. The lithium choride concentration was further varied from 8 M to 13 M (43.24) weight percent) to gather data beyond those of other researchers. Similar to the trend of water diffusivity in lithium bromide solutions, water diffusivity in lithium chloride solutions was also found to vary with concentration with a minimum of 6.2 x 10(-10) m(2)/s near the solubility limit.