Abstract: A method for the determination of diffusivities in liquids is described; the method is based on measurements of the response to injection in a laminar flow of liquid in a capillary. By injection of δ-type, the component whose diffusivity is to be measured is introduced into the inlet part of a capillary of internal diameter 1.6 mm. The response to the injection is measured at the end of the capillary by a flow-through refractometer, the output signal of which is recorded on tape at 16-s intervals. The output signal is compared with a theoretical model of the time dependence of the response, based on Taylor's analysis of the dispersion of an injected component in laminar flow. The diffusivity is calculated from one of the model parameters, which were evaluated by the method of maximum likelihood. The calibration of the instrument was performed by measuring the diffusivity of KC1 in aqueous solution. The following diffusivities at 25°C were determined: n-butanol 971 µm2/s, dioxane 1093 µm2/s, caprolactame 948 µm2/s, Na2SO4, 1126 µm2/s, salicylaldoxime 895 µm2/s, cyclohexanone 960 µm2/s, acetone 1316 µm2/s, oxine 820.5 µm2/s, all in water; caprolactame in trichlorethylene 1958 µm2/s, caprolactame in 10% aqueous (NH44)2,SO4 solution 1148 µm2/s, salicylaldoxime in chloroform 1878 µm2/s.